A Consistent Picture? Issue‐Based Campaigning on Facebook During the 2021 German Federal Election Campaign

: This article is


Introduction
Social networking platforms, with their sophisticated algorithms for targeted and personalized messaging, have revolutionized the way political messages are produced and disseminated (Römmele & Gibson, 2020;Votta et al., 2024).Notably, Facebook is leveraged by parties to understand and respond to voter preferences, develop targeted communication strategies, and interact with the electorate (Kreiss, 2016).This influences various strategic aspects of a campaign, such as issue prioritization (e.g., Dobber & de Vreese, 2022;Hillygus & Shields, 2009;Kruikemeier et al., 2022).Since party identification is tending to decline (Dassonneville et al., 2012), short-term factors, such as convincing voters by prioritizing certain political issues, are becoming increasingly important for parties' campaigns.
In general, two broader strategies for how parties emphasize issues during election campaigns are discussed in the literature: They can either focus on issues where they have issue ownership (the issue ownership strategy; Budge & Farlie, 1983;Petrocik, 1996) or they can focus on issues that are of great concern to the voters at the time of the election (the riding-the-wave strategy; Ansolabehere & Iyengar, 1994; for an overview see also Wagner & Meyer, 2014).Previous research on parties' strategic issue prioritization has intensively focused on party manifestos (e.g., Wagner & Meyer, 2014), press releases (e.g., Klüver & Sagarzazu, 2016;Seeberg, 2022), and social media (Twitter: De Sio & Weber, 2020;Facebook: Ennser-Jedenastik et al., 2022), and investigated whether parties are consistent in the topics they emphasize across different communication channels (e.g., Elmelund-Praestekaer, 2011;Ivanusch, 2024;Norris et al., 1999;Tresch et al., 2018).
Our study aims to extend current research by comparing different post types within one platform, namely organic and paid posts on Facebook.Facebook is the most intensely used social networking platform in many Western democracies and focusing on this platform allows us to compare strategies that are free of charge to strategies that parties pay for.Organic posts are regular posts that page owners (here: political parties) post to appear on their Facebook page.These organic posts are also shown on the timelines of the page's followers.
Sponsored posts are organic posts that are "boosted," that is, paid for, to reach specific audiences beyond the followers of a page.Facebook ads are paid advertisements that are shown on the timelines of targeted users.Ads can be used to reach even more finely defined target groups with various advertising objectives, such as increased traffic or engagement (Kruschinski & Bene, 2022).By comparing these post types, we seek to answer the central question of whether parties consistently emphasize an issue ownership strategy or a riding-the-wave strategy in the different post types (organic posts, sponsored posts, and ads) and whether parties spend more money to spread owned issues or issues important to voters.
To this end, we conducted a quantitative content analysis of all organic posts, sponsored posts, and ads from all seven German parliamentary parties in the four weeks before the 2021 federal election ( = 1,029 posts,  = 1,197 sponsored posts,  = 2,643 ads).The identified issues highlighted in the posts were matched with survey results from the German Longitudinal Election Study (GLES) on the importance of issues in the week before the election and the problem-solving skills that respondents associated with the German parties (Debus et al., 2023;Roßteutscher et al., 2023).
Our results provide important insights into how parties in a European country with strict EU data protection regulations spend their money on the most far-reaching social networking platform to emphasize campaign issues and whether the underlying strategy complements or extends the strategy applied "for free" in the organic posts.Thus, our study presents important descriptive data upon which future studies that investigate targeting decisions on social networking platforms can be built.

Political Campaigning With Facebook's Organic and Paid Media
Facebook, with its vast user base and strategic functionalities, has emerged as a pivotal social networking platform in political campaigning (Haßler et al., 2021).The platform's capabilities for organic (i.e., regular posts) and paid media (i.e., sponsored posts and ads) are integral to today's political marketing strategies (Kruschinski & Bene, 2022;Stuckelberger & Koedam, 2022).Both media types offer direct access to voters as they bypass traditional journalistic gatekeeping, yet they differ in cost, production, marketing objectives, and audience reach.
Organic media on Facebook allows political actors to post content on their pages at a low cost, reaching users who follow their page and potentially the networks of these users when they share and like the posts.This form of media is particularly advantageous for campaigns with an engaged followership or limited budget, providing direct access to supporters without having to rely on coverage in the traditional mass media (Kalsnes, 2016;Ross et al., 2020).
Paid media enables political campaigners to pay for the distribution and targeting of messages to specific users on the platform in two ways.While sponsored posts are organic posts that are boosted with payment to reach a wider, targeted audience, Facebook ads are tailored for specific campaign objectives and do not appear on the advertiser's Facebook page.In comparison to the very basic advertising capabilities of sponsored posts, ads require more sophisticated marketing skills and offer nuanced targeting options, making them suitable for advanced campaign strategies (Kruschinski & Bene, 2022).

Issue Prioritization in Parties' Campaign Communication
Research indicates that electoral campaigns strategically assess Facebook's organic and paid media in line with their broader marketing strategies, tailoring their messaging and resource distribution accordingly (Kruschinski et al., 2022).This adaptation includes considerations about timing and content in light of party characteristics.
Content strategies regarding political issues are of special importance, as they allow parties to emphasize their stances on current political topics while simultaneously enabling voters to connect parties to issues salient to them (Ansolabehere & Iyengar, 1994;Hillygus & Shields, 2009).
In German federal and state elections, political parties strategically utilize their Facebook pages for issue management (e.g., Magin et al., 2017).This involves a systematic approach of observing, analyzing, selecting, coordinating, and controlling communication to assert dominance in public debates on specific issues.
The core strategy is to proactively emphasize favorable issues (Tresch et al., 2018) with the underlying objective of shaping and influencing voter preferences (Ansolabehere & Iyengar, 1994).
Two ideal-typical main strategies of parties for selecting possible policy topics are discussed in the literature: issue ownership and riding the wave on publicly salient issues.
The issue ownership hypothesis suggests that parties focus their campaign efforts on issues that they are identified with and perceived as competent in addressing by the electorate (Budge & Farlie, 1983;Petrocik, 1996).Empirical studies indicate that emphasizing the issues a party "owns" can provide electoral attention and advantages at the polls (Karlsen & Aardal, 2016;Kleinnijenhuis & Ridder, 1998;Lefevere et al., 2015).Thus, it is crucial for parties to continually remind voters of their key issues, utilizing direct communication channels like Facebook to sustain issue ownership (Kruschinski et al., 2022).
Issue ownership in the German political landscape is typically stable, a result of a party's historical focus and achievements in specific areas (Seeberg, 2017;Walgrave et al., 2009).Despite a trend toward ideological convergence among parties, voters tend to distinguish them based on their issue-handling capabilities (Kleinnijenhuis & Ridder, 1998).The priority for voters remains the party's ability to address current and relevant problems.Conservative parties, akin to the CDU/CSU, are often seen as more capable of handling economic, security, and fiscal issues.Right-wing parties, like the AfD, are typically associated with immigration, national identity, and security concerns.On the other hand, socialist and social democratic parties like the Left party and the SPD are perceived as more competent at addressing social issues like unemployment, welfare, and healthcare.The Greens in Germany are primarily identified with environmental issues, including climate change and sustainable energy policies (Seeberg, 2017).In multi-party systems like Germany's, of course, attempts to "steal" issue ownership from other parties or to "become associative owners of issues" are possible, meaning that different parties can compete for ownership of the same issues (Walgrave et al., 2015, p. 789).
However, concentrating only on owned issues might lead to the public impression that the party is ignoring important current issues if the owned issues are not the most salient issues for citizens.As an alternative, parties can engage more in topics from the media agenda and from their political rivals (Seeberg, 2022), and therefore "ride the wave" of currently salient topics (Ansolabehere & Iyengar, 1994).In doing so, parties show responsiveness to the upcoming issues that most concern the citizens (Ennser-Jedenastik et al., 2022;Klüver & Sagarzazu, 2016).
Both strategies have been observed empirically with some studies supporting the use of the issue ownership strategy (e.g., Walgrave et al., 2015), while others show the use of the riding-the-wave strategy (e.g., Klüver & Sagarzazu, 2016).Furthermore, different parties can use different strategies in different communication channels, for example, depending on their institutional organization (Wagner & Meyer, 2014).Seeberg (2022) interprets these inconclusive findings in view of the different communication channels used by the parties and at different points in time in the election campaign, considering issue ownership as a long-term strategy and riding-the-wave as a short-term strategy.This reflects the relative stability of issue ownership based on their social origins (Petrocik, 1996;Walgrave et al., 2009) as well as the responsiveness of parties when reacting to sudden events (Dalmus et al., 2017).Therefore, since parties do not necessarily have to prioritize the same issues in different communication channels (Seeberg, 2022;Tresch et al., 2018), both strategies can be applied by the same party.A third approach extends the issue ownership concept: The issue yield approach assumes that it is profitable for parties to focus on issues on which both the electorate as a whole and their own supporters attribute the party a high level of problem-solving competence and which also dominate the current issue agenda (De Sio & Weber, 2020, pp. 723-725).It cannot be denied that a distinction between the assessment of the problem-solving competence of parties by the entire electorate and the party supporters can be conceptually fruitful, but for reasons of stringency we focus here on the ideal types of the issue ownership and riding-the-wave strategies.

Issue-Based Messaging Strategies in Organic and Paid Posts on Facebook
As Facebook's organic and paid media differ in cost, production, marketing objectives, and audiences, it is worthwhile to investigate how these differences influence the strategic prioritization of policy issues.
However, only limited research exists on the comparison of organic and paid messaging strategies of different political parties on Facebook with a specific focus on strategic issue management (cf.Kruschinski et al., 2022).
Organic posts on Facebook allow political parties to reach a broad audience, typically consisting of their established supporters.Thus, these posts often focus on consensus-driven topics that resonate with a party's core ideology and principles (Kruschinski et al., 2022).The autonomous nature of organic media means that parties have full control over the content and messaging, which is crucial for maintaining a consistent party image and ideology (Stier et al., 2018).Manual content analyses reveal that European parties put an emphasis on consensual policy issues in their organic posts that are traditionally connected to their party (Lucht et al., 2017), a phenomenon that can also be witnessed in German state elections (Kruschinski et al., 2022).
Based on these insights, we argue that German parties strategically steer debates towards issues they "own" in their organic Facebook posts.This leads to the first hypothesis: H1: German political parties predominantly employ an issue ownership strategy in their organic posts on Facebook.
In contrast to organic posts, sponsored posts and ads on Facebook offer targeted and personalized message delivery to specific segments of the electorate.This targeting is often based on issues presumed to be of interest to these segments, aiding in the development of a unique party image (Kruikemeier et al., 2022;Votta et al., 2024).While organic posts tend to embrace broader, consensus-driven topics that resonate with the party's core supporters, paid media facilitates more tailored and potentially divisive campaigning.Thus, it could lead parties to focus on wedge issues that may appeal to diverse voter segments with varying viewpoints (Kruikemeier et al., 2022).
Despite the potential for such audience-segmented issue strategies, research indicates that parties often choose to focus on established, non-controversial issues in ads.Evidence from studies conducted in the US and Canada suggests that parties reinforce their own core messages with ads that resonate with their primary voter base, who are more likely to be receptive to these familiar topics (Bennett & Gordon, 2021;Fowler et al., 2020).This cautious approach is likely due to the high stakes of elections, where missteps in communication can have significant electoral repercussions.However, other research in Germany indicates that parties tend to use more diverse issues in their ads, especially in their sponsored posts (Kruschinski et al., 2022).
Given these discrepancies in the current literature, we want to find answers to the following research questions: RQ1: Do German political parties employ an issue ownership strategy or a riding-the-wave strategy in their sponsored posts and ads on Facebook?RQ2: Do German political parties spend more money on sponsored posts and ads employing an issue ownership strategy or a riding-the-wave strategy?

Method
To test our hypothesis and answer our research questions, we conducted a manual quantitative content analysis of parties' organic and paid Facebook posts-including organic posts, sponsored posts, and ads-during the 2021 German federal election campaign.We focused on parties in the national parliament: the conservative Christian democratic CDU/CSU, the social democratic SPD, the liberal FDP, the Green party (Bündnis90/Die Grünen), the left-wing Left party (Die Linke), and the right-wing populist AfD.
All Facebook posts published on the pages of the national parties during the hot election phase four weeks before the election (August 30, 2021-September 26, 2021) were collected daily using the application programming interface (API) of CrowdTangle.The ads and sponsored posts were collected using Meta's AdLibrary API.The cleaned sample contains 1,029 organic posts, 1,197 sponsored posts, and 2,643 ads.
Germany, with its mixed-member electoral system and multi-party system, represents a special case among Western democracies (Tomuschat, 2013).As such, the theoretical underpinnings of election campaign communication strategies might differ from those of parties in other countries.Nonetheless, our focus on Facebook-as in many countries the most popular social networking platform in Germany in 2021 (Newman et al., 2022)-provides a starting point for comparisons with online strategies of parties in other countries, as the digital architecture (Bossetta, 2018) of Facebook remains constant between different countries where parties use Facebook as a communication channel.Our analysis can serve as a reference to compare the campaign strategies of different parties in organic posts, sponsored posts, and ads on Facebook.
The organic posts were coded by six coders.For the sponsored posts and ads, all categories were coded by four coders.All coders were intensively trained in the coding scheme.Reliability tests with 100 organic posts coded by all coders in the organic posts team and 60 paid posts coded by all coders in the paid posts team indicate a common understanding of the coded categories (see Table 1).We used Brennan & Prediger's Kappa (B&P Kappa) as an indicator for reliability because we utilized binary variables and the underlying data was often zero-inflated.In such cases, B&P Kappa has been shown to be a valid and robust chance-corrected indicator (Quarfoot & Levine, 2016).Holsti is reported as a second reliability indicator.
We measured which issues a post addressed to detect whether parties used an issue ownership or a riding-the-wave strategy.Policy issues could have been addressed in text elements (text of the post, slogan, quote) as well as visual elements (i.e., the image, the first minute of a video, the preview of a link, or the first image of an album).The issues were considered independently from each other to code as many different issues as were present in the post.
Policy issues addressed in the posts were measured in fine-grained detail.To match the post content to the data from the GLES, broader policy issues were recoded from the original coding (see Table 1).Therefore, we differentiated eight different policy issues: (a) "environment," whenever posts addressed climate change, safety of endangered species, or policy to save forests; (b) "Covid-19" when Covid-19 case numbers or measures against Covid-19 were addressed in the post; (c) "social issues" when topics such as pensions, rents, wages, or working hours were mentioned; (d) "domestic policy" when topics such as criminality/crime rate, political radicalism, disaster management, or flood protection, or topics related to immigration or the integration of refugees were addressed; (e) "economy" when topics such as the European crisis, austerity measures, trade agreements, or protectionism were mentioned; (f) "infrastructure" when public transportation, Autobahn or electrical infrastructure, and digitalization were mentioned; (g) "foreign policy" when the post addressed international relations between states, development policy, or the arms trade; and (h) "other" if a post dealt with a topic that did not fit into these categories.
The amount of money spent for sponsored posts and ads by each party was analyzed using the data from Meta's AdLibrary API.Since Meta only provides intervals of the money spent in the form of "lower" and "upper" boundaries, we calculated a midpoint of these values by using the mean value to be able to compare the amounts of money spent between parties and between issues.
To identify the most salient issues and to introduce an external empirical indicator of issue salience among voters and issue ownership of parties, we combined the content analysis with a secondary analysis of the data from the GLES.In the GLES Tracking Study from September 2021, 1,688 people were asked between 15 and 24 September (10 days before the election) what they think is currently the most important political problem in Germany (Debus et al., 2023).These answers were summarized in various thematic categories (Roßteutscher et al., 2023).Participants were also asked which German party was best qualified to solve this problem (attributed solution competence of the parties).In a first step, we focused on the top 10 most important political problems.To match these top 10 with the topics coded in the content analysis, "environmental policy" and "climate policy" were recoded to "environmental and climate policy."Similarly, "social justice," "pensions and demographic change," "poverty," and "housing" were recoded to "labor and social policy."The variable names of the GLES were adopted as far as possible.Since the issue "values, political culture and social criticism"-in 9th place in the GLES list-is not a single policy field, but affects more or less all policy fields, we did not include this issue in our analysis.As a result, we have created a top 5 list of the most important topics from the GLES data, which is comparable to the data from the content analysis (see Table 2).
A disadvantage of this approach is that the two GLES items measure the salience of issues by asking for the respondents' opinion as to what the most important political problems would be and the problem-solving competence for these most salient issues (for a discussion of the challenges in measuring issue salience see Wlezien, 2005; for a discussion of issue concerns of different party electorates see Neundorf & Adams, 2018).
However, we consider the ascribed problem-solving competence on the most important issues as measured by the GLES to be a good benchmark for discussing the issue strategies of parties on Facebook.

Results: Issue Ownership or Riding-the-Wave in Organic and Paid Posts on Facebook
The secondary analysis of the results of the GLES data shows that, in the run-up to the 2021 federal election, German citizens primarily rated environmental and climate policy as important for Germany ( = 336; see Table 2), followed by issues related to the Covid-19 pandemic ( = 283), labor and social policy ( = 255), immigration and integration policy ( = 218), and economic policy ( = 65).The GLES data provides empirical insights into the issue ownership approach, when asking the participants about the party with the highest problem-solving competence: In the case of environmental and climate policy, most participants stated that the Green party was best suited to solve these problems (50%).For immigration and integration policy, most participants named the AfD as the most competent problem solver (55%), while the CDU/CSU was named most frequently for problems regarding economic policy (29%).When it came to the problems surrounding the Covid-19 pandemic and social issues, most participants stated that no German party was particularly Notes:  = 1,157; top 5 most frequently mentioned problems in Germany combined with information on which parties citizens ascribe the problem-solving competence for these problems (percentages); the top 5 exclude "no response," "other," and "not specified/not applicable"; cells marked in dark contain the most problem-solving competence attributions by the participants; lighter colored fields are the alternative if "none of these parties" was mentioned most frequently; sums deviating from 100 result from rounding errors; read: 10% of 336 respondents who named "Environmental and climate policy" as the most important problem also found the CDU/CSU to be best suited to solve the problems regarding this issue.Source: Debus et al. (2023).
well-placed to solve these problems.Compared with the other parties, the CDU/CSU is considered to have the best problem-solving skills in relation to the pandemic (21%) and the SPD in relation to social issues (27%).
The FDP and the Left party did not reach the highest problem-solving competence scores in any of the top 5 issues.The FDP achieved its highest scores in terms of problem-solving competence in economic policy (14%).
The Left party's highest scores were reached in the field of labor and social policy (17%).
Focusing on the posting activity of the parties on Facebook, it can be observed that the parties pursued different strategies (see Table 3).Most parties relied heavily on paid ads since they published more ads than organic and sponsored posts.Most strikingly, the FDP published 1,681 paid ads compared to 117 organic posts and 879 sponsored posts.In contrast to this strategy, the Christian conservative CSU published more organic posts ( = 225) than sponsored posts ( = 9) and ads ( = 14).The right-wing AfD used organic posts ( = 160) and paid ads ( = 164) in equal measure.In the mix of communication channels, Facebook and, in particular, the various types of (paid) posts and ads were attributed varying degrees of importance by the parties, potentially depending on the size of the party, the assumed electorate, and the money available for the campaign.However, all parties were active to a certain extent and also invested money during the election campaign on Facebook.
In their organic posts, the social democratic SPD and the Left party both most frequently referred to labor and social issues (see Figure 1).This issue can be labeled as owned by the SPD, since of all parliamentary parties the social democrats scored highest regarding the problem-solving competence on this issue.Overall, it can be concluded that in the organic posts, German parties relied heavily on an issue ownership strategy, supporting H1.Especially the Greens and the SPD published more posts on their owned issues than on all other issues combined.For the Greens, the most publicly salient issue fell together with their owned issue of environmental and climate policy.Thus, they could ride the wave and emphasize their owned issue simultaneously.Instead of riding the wave on the most publicly salient issue, the CDU/CSU and the AfD referred to their owned issues.The Left party referred to the issue where it reached its highest competence scores.The FDP most frequently referred to labor and social issues.In doing so, it was the only party that focused on a topic other than the one where it reached its highest competence scores.
The picture is similar for sponsored posts-apart a few minor deviations (see Figure 2).The Greens, SPD, CDU, and AfD most frequently referred to their owned issues in sponsored posts.The Greens, who sponsored a total of only three posts, exclusively sponsored posts that highlighted environmental and climate policy and could combine the issue ownership and riding-the-wave strategies.Again, the Greens and the SPD published more sponsored posts with their owned issues than on all other issues combined.In the sponsored posts, the FDP highlighted economic policy and not-as was the case in the organic posts-labor and social issues.The AfD kept highlighting immigration and integration policy issues and the Left party focused on labor and social issues.Interestingly, the Christian conservative regional party CSU deviated from their issue ownership strategy in the organic posts and highlighted labor and social issues instead of economic policy in their sponsored posts.Still, overall, parties also used an issue ownership strategy in their sponsored posts.
The SPD, the Greens, the CSU, and the AfD also followed the issue ownership strategy in their paid ads: The SPD addressed labor and social issues most frequently, the Green party dealt with environmental and climate change policy, the conservative CSU spoke of economic policy, and the AfD focused on immigration and integration policy (see Figure 3).Yet, there are some interesting specifics.The issue ownership strategies of the Greens and the SPD are not as pronounced in their paid ads as in their organic or sponsored posts.That is, the percentage share of ads referring to their owned issue-and the riding-the-wave issue of environmental and climate change policy in the case of the Greens-is not as high as in the organic or sponsored posts and the second most frequent issue comes close after the issue in first place.Furthermore, the Left party kept highlighting labor and social issues in their paid ads, while the CDU most frequently addressed foreign policyan issue not owned by the party and not even among the top 5 topics-and the FDP again highlighted labor and social issues.
The analysis of the total advertising spending per policy issue (see Figure 4) shows that almost all parties spent the most money to spread posts featuring labor and social issues.Focusing on this issue translates to an issue ownership strategy for SPD.AfD alone relied on spending the most money on another issue-immigration and integration policy-that was also owned by the party.The CSU spent the most money on posts featuring transport and infrastructure policy.
Thus, five out of the seven parties believed that their money was best spent on spreading posts and ads highlighting labor and social issues, and three parties did so without issue ownership.It can be assumed that the parties believed that this issue would help persuade voters who could be reached with paid posts.
Interestingly, the results of the GLES showed that labor and social issues were not the top-ranked issues among the most important topics considered by citizens.Instead, the Green party especially could have amalgamated an issue ownership with a riding-the-wave strategy by paying the most money for posts highlighting environmental and climate policy.

Conclusion, Limitations, and Outlook
The results of our analysis show that the parties pursued different strategies of issue prioritization with regard to the target groups that follow their Facebook pages as opposed to the target groups that do not follow their page but can be reached with paid advertising.Overall, it can be concluded that German parties broadly relied on issue ownership strategies in their communication during the 2021 federal election campaign.This strategy can be found in the parties' organic posts (H1), sponsored posts, and paid ads when looking at the mere frequency of posts on specific policy issues produced for the campaign (RQ1).In organic posts, the frequency can be interpreted as an indicator of what posts Facebook users see when they visit the party's Facebook page or what the followers of a party's page see on their own timelines when the party publishes a post.For their organic posts, it can therefore be assumed that the parties believe that their followers-who are generally positive about the party anyway (Fisher et al., 2019)-are interested in the party's owned issue (Ennser-Jedenastik et al., 2022) and can best be mobilized with posts about the party's position on this issue.
Since sponsored posts are organic posts that parties pay for to reach audiences beyond their page followers, the fact that parties frequently spread posts containing owned issues shows that they did not assume issue ownership to be generally worthless when targeting audiences that do not follow the party's own Facebook page.The results for the frequencies of paid ads with specific issues suggest a similar interpretation at first glance.Yet, in the case of sponsored posts and paid ads, these frequencies should not be interpreted as a direct result, but should be weighted according to the amount of money spent on the paid content.Paid ads are especially used for targeting (very) specific audiences or for so-called A/B testing (Dommett & Power, 2019).
In an A/B test (slightly) different versions of messages are presented to different audiences to test which version, for example, generates more clicks.Thus, there might be sponsored posts and ads in the dataset that were only shown to comparatively small fractions of Facebook users.The number of people who see an ad addressing a specific issue depends on how much a party pays to display this ad to targeted people on their Facebook timeline.
To analyze which issues the parties wanted to make prominent on the social networking platform, we also analyzed how much money the parties spent on sponsored posts and paid ads addressing the issues under investigation.Surprisingly, the results of this analysis indicate that all parties-except the CSU and the AfD-emphasized social issues (RQ2).From a theoretical perspective, highlighting social issues could make sense if one assumes that party positions, especially on social issues together with economic issues, effectively influence voter decisions (Stoetzer & Zittlau, 2020).However, our results only partly reflect this relation, since we find that parties spent money to spread messages on social issues to a much greater extent than economic issues.Furthermore, the GLES data showed that social issues were not the striking "super issue" during the 2021 election campaign overshadowing other issues.On the contrary, social issues ranked in third place concerning the most salient issues.
Overall, various explanations for the pattern of our results are conceivable.First, parties could apply different strategies for different audiences.An issue ownership strategy targeting page followers could be complemented by a strategy explicitly targeting audiences interested in social issues.Second, it could be the case that the pattern only emerged because sponsored posts and paid ads are more expensive for groups that are not generally in the "organic reach" of a party (e.g., as they differ from the group usually following the party page).Thus, Facebook could demand higher prices for sponsored posts and ads that do not highlight owned issues.Third, the parties may have identified social issues as important during the campaign and responded to this trend by simply investing more money in posts that contained the trending topic and that were already in their inventory of posts and ads, rather than producing additional variations on that topic.Overall, our results provide only a starting point for further analyses of the reasons for the strategic decisions of the campaigners.Further insights can be gained by, for instance, analyzing the impressions paid posts generated per euro or looking at the chosen targeting criteria and audiences to find more explanations for the selection of different issue strategies.
While providing valuable insights, our results have to be interpreted with caution because especially the data availability on money spent for paid posts is not ideal.Meta provides only lower and upper boundaries of the actual amount spent for the paid posts.In addition, more detailed information on targeting criteria and actually reached audiences with organic and paid posts would add much-needed transparency in the field of digital election campaigning.Further, the choice of Germany and Facebook as our study's context may limit the generalizability of findings.Including other countries (e.g., with different party or electoral systems) and social networking platforms would add more information about digital issue campaigning.In addition, analyzing longer or different phases of political communication outside of the last weeks and days before the election could provide important insights into political issue strategies in general.
Nonetheless, our study provides important insights into the strategies that parties implement when Our results can have an impact on decisions made by political parties or campaign strategists, for instance, when planning cross-platform campaign strategies or when weighing up the ethical implications of providing different election-relevant information to different target groups.Understanding strategic issue management in digital spaces is crucial for effective and responsible political communication, and policymakers might use these insights to inform the evolving landscape of digital advertising regulations.

Figure 1 .
Figure 1.Percentage share of policy issues addressed in organic posts.Notes: The investigation period was August 30, 2021-September 26, 2021;  = 1,029 posts; gray bars suggest the issue was not among the top 5 most salient issues.

Figure 4 .
Figure 4. Amount of money spent for sponsored posts and ads containing different policy issues.Notes: Investigation period was August 30, 2021-September 26, 2021;  = 3,840 sponsored posts and ads; gray bars suggest the issue was not among the top 5 most salient issues.
prioritizing issues in their election campaigns.By delving into strategic issue management in digital political marketing, this research fills a significant gap in the literature.It offers empirical evidence of how political parties adapt their communication strategies in the digital sphere, particularly in managing issues and allocating advertising resources, thereby contributing to a deeper understanding of digital political marketing dynamics.Future research can build upon our results to analyze what effects these strategies have on voters, whether and how different parties use different issue strategies in different post types or different channels, how the strategies fit in the overall campaigns of parties, and whether digital campaigning leads to a fundamental change in how politics is presented to the public.

Table 2 .
Salient issues to the public during the 2021 German election campaign and issue ownership.

Table 3 .
Number and percentage shares of posts, sponsored posts, and paid ads.The investigation period was August 30, 2021-September 26, 2021; the numbers of sponsored posts and ads include "duplicates" used for A/B testing; in an A/B test (slightly) different versions of messages are presented to different audiences to test which version generates more clicks. Notes: Percentage share of policy issues addressed in paid ads.Notes: Investigation period was August 30, 2021-September 26, 2021;  = 2,643 ads; gray bars suggest the issue was not among the top 5 most salient issues.