Abstract
Introduction
After a decade during which the European Union (EU) has been riddled by a multi-faceted crisis and increased politicization, the 2019 election to the European Parliament (EP) was accompanied by the dictum that the future of Europe is at stake (Braun, 2021; Treib, 2021). While similar debates in the past, such as around the introduction of the
The suggestion that a more intense debate over European issues in the run-up to the elections positively impacted individual participation in the 2019 EP election, is reinforced by a simple observation: despite the rise in turnout across Europe, there is still a considerable variance in the absolute participation levels between the EU member states (see Figure 1(a)). Importantly, such differences are also visible when we take a look at the most important mobilizing issues during the 2019 EP election (see Figure 1(b)). When being asked about the issues that ‘made you vote in the recent European Parliament elections’, the majority of people in many countries reported that the economy was key for their participation. However, in other countries the strongest mobilizing issues were climate change, immigration, or European integration. Observing such a variance might seem surprising, but it indicates the persisting second-order nature of EP election campaigns, where issues are discussed by national actors in national public spaces (Boomgaarden and De Vreese, 2016). The intriguing question is how relevant these issues were for voter turnout in the 2019 EP election and which issues exerted the strongest mobilization power. To answer these questions, we need to shift the focus from the macro-level to the citizen-level and delve into the micro-foundations of the relationship between policy issues and electoral behavior.

Turnout levels and most important mobilizing issues in the 2019 EP election across EU member states.
This article explores whether and through which mechanisms policy issues affect electoral participation. In particular, we investigate the impact of the four major transnational policy issues ‘economy’, ‘immigration’, ‘environment/climate change’ and ‘European integration’ on individual electoral participation. We argue, first, that EU citizens showed a higher tendency to participate in the 2019 European election when they attributed a greater relevance to one or more of these issues, meaning that they found an issue to be salient or held a rather extreme opinion on a policy issue. Second, we argue that people were more likely to vote when the policy issues they subjectively found most relevant were also systemically salient in their country. Our empirical analyses are based on two different data sources: the large-scale post-election study of the Eurobarometer (EB 91.5) comprising all 28 EU member states (at the time of the election) as well as the original panel survey data for seven selected EU countries taken from the H2020 project RECONNECT. The findings reveal the context-dependent nature of issue mobilization during EP elections and bear important implications for the legitimizing role of EP elections and the future of European integration.
Policy issues and European elections
Although we know a lot about the factors fueling and hindering citizens’ participation in elections, much less is known about the peculiar link between policy issues and the decision to vote. Do citizens go to the ballot box because specific issues matter to them or their country? In other words, do political issues mobilize citizens? And does such a relationship also hold for EP elections?
Policy issues and the individual decision to vote
We know from Down’s (1957) famous insights on rational voting behavior that voters generally have rather low incentives to become deeply informed about specific policy issues. However, elections are contests that ‘are fought over policies and issues that voters, parties, and leaders consider to be important and relevant at the time of the election’ (Aardal and van Wijnen, 2005: 192). Therefore, it is intuitively plausible that central policy issues and voter turnout should be linked to some degree. One could even make a stronger claim: failing to account for policy issues in the research on electoral participation would mean taking ‘politics out of elections’ (Aaardal and van Wijnen, 2005: 192).
Accordingly, the scholarly literature presents empirical evidence indicating a relationship between policy issues and turnout. For example, countries with high electoral salience and fierce competition over political issues report higher turnout rates (Franklin, 1996; Pacheco, 2008). For the US, we see that citizens’ probability of turning out in elections is higher if they perceive differences in issue positions between candidates (Adams and Merrill, 2003; Adams et al., 2006; Leighley and Nagler, 2014; Zipp, 1985). Equally impressive are more recent studies on ‘policy representation’ illustrating that the congruence between voters and political parties over particular, salient political issues affects electoral participation (Dinas et al., 2014; Lefkofridi et al., 2014; Reher, 2014). Finally, Kiousis and McDevitt (2008) shed light on the process behind the link connecting issues and turnout. They show that greater news attention during election campaigns increases individual ‘issue importance’ and ‘opinion extremity’, which eventually furthers the chance of electoral participation.
Although we lack similar studies regarding European elections, investigating EP elections can significantly contribute to our understanding of the relationship between policy issues and electoral participation. First, EP elections create an opportunity to investigate a simultaneously conducted set of elections in various countries and electoral contexts (Söderlund et al., 2011; Van der Eijk et al., 1996). This feature implies that EP elections are well suited to test the effects of different issue contexts. Second, turnout in EP elections is traditionally rather low, which is mostly attributed to the perception that there is ‘less at stake’ compared to national first-order elections (Franklin and Hobolt, 2011; Reif and Schmitt, 1980; Schmitt and Mannheimer, 1991; Van der Eijk and Schmitt, 2009). However, the rising turnout in the most recent EP elections might indicate that there is now ‘more at stake’ and that key policy issues mobilize people across the continent. Empirical findings from previous EP elections support this argument. Although Clark (2014) shows that the lower salience of issues under the jurisdiction of the EU can explain the reduced turnout in European elections, many scholars from the ‘Europe matters’ camp find that the issue of European integration indeed plays a role in present-day European elections. Besides the well-known ‘EU issue voting’ argument that is imperative for the decision to vote for a party (De Vries, 2010; De Vries and Hobolt, 2016), EU attitudes are relevant for turnout. While pro-EU attitudes bolster the chance of electoral participation (Braun, 2021), non-voting in EP elections is motivated by Eurosceptic attitudes (Blondel et al., 1998; Clark, 2014; Hobolt and Spoon, 2012; Hobolt and Wittrock, 2011; Schäfer, 2021; Wessels and Franklin, 2009). In a similar vein, Schäfer and Debus (2018) demonstrate that issue congruence between voters and political parties matters for participation in EP elections and that this relationship has strengthened during the Euro crisis. Against this backdrop, we assume that turnout rose in the 2019 EP election because citizens perceived that there was more than the usual at stake in these elections and because several policy issues at the EU level were highly politicized during the election campaign.
The key mobilizing issues in the 2019 European Parliament election
The 2019 EP election was held at a time when a limited number of key issues mattered to voters across EU member states – yet to a varying degree in each country (see Figure 1(b)). Besides this inductive approach of identifying the most relevant policy issues from survey data, we also provide theoretical arguments for our interest in the mobilizing role of four main issues: the economy, immigration, environment/climate change, and European integration. In the following, we argue why these four issues were highly politicized among the European publics during the 2019 EP election campaigns and why they should be related to the increase in turnout.
It is commonplace to say: ‘when you think elections, think economics’ (Tufte, 1978: 65). But apart from the central role of the economy in elections more generally,
Second,
Third, concerns over climate change have brought
Lastly, the
The link between policy issues and electoral participation
Based on previous research regarding the relation between policy issues and electoral participation, we argue that the link between the key policy issues and the individual’s decision to turn out during European elections functions through two direct and one indirect channel. First, EU citizens should be more inclined to vote when they perceive a major transnational policy issue as highly important. Second, people should feel more incentivized to participate in an EP election when they hold an extreme opinion on a key policy issue. These two direct channels imply that both meta-attitudinal cognitions (such as issue importance) as well as more operative forms (such as attitude extremity) affect political behavior (Bassili, 1996). Third, the public relevance of certain policy issues should enhance the mobilization effect of personal issue importance among the citizens of this country.
The relevance that a person attaches to a policy issue can be called personal ‘issue salience’ or ‘issue importance’ (Fournier et al., 2003). Some scholars understand personal issue salience as ‘a political attitude like any other’ (Dennison, 2019: 443), exerting direct and indirect effects on many political behaviors. Other authors see issue importance as a form of ‘attitude strength’ but also find that it affects voting behavior (Bassili, 1996: 637–8). On a more general note, we can assume that personal issue importance is related to political awareness and political interest (Zaller, 1992). From previous research, we know that people who are politically interested and informed have a stronger tendency to participate in elections (Delli Carpini and Keeter, 1996; Lassen, 2005; Smets and van Ham, 2013) – which is also true for EP elections (Bhatti, 2010; Braun and Tausendpfund, 2019; Hogh and Larsen, 2016; Schäfer, 2019).
Accordingly, the more people become interested and competent in political matters, the more likely they are to form political attitudes and attach importance to different policy issues. This assumption implies that, the individual perception of relevance of certain policy issues – whether for herself (ego-centric motivation) or for the country she lives in (socio-tropic motivation) – is consequential for politics. We then expect that this person has an increased tendency to follow political events, receive political information and participate in political decision-making processes. Consequently, in our first hypothesis we argue that the act of electoral participation can be understood as a mean to put personally relevant policy issues on the agenda of the entity or institution a person votes for – in our case, the EP or the EU more generally.
However, insights from social psychology suggest that salience effects do not represent the only impact that policy issues have on electoral participation. Building on the notion of ‘opinion extremity’ (Kiousis and McDevitt, 2008), we assume that people make their electoral participation dependent on whether they have a strong view on a particular policy issue relevant in the elections. More specifically, we argue that voters feel incentivized to participate when they want to express a strong (i.e. extreme) preference, whereby extreme is defined as ‘the extent to which the attitude deviates from neutrality’ (Krosnick and Petty, 1995: 6). Strong opinions on policy questions signal that people perceive an issue to be ‘at stake’, especially during an election. From this perspective, electoral participation can be seen as an attempt to shape future policies in line with preferred policy positions by supporting a political party representing these positions. In contrast, people with more ambivalent, neutral, or indifferent opinions on policy issues should have lesser incentives to participate in an election because there clearly is ‘less at stake’ for them.
Lastly, it is not only
Taken together, we argue that the combination of high personal issue importance and high systemic issue salience should have an additional effect on electoral participation. Compared to the two individual-level mechanisms described before, we put forward at this stage a systemic argument of contextual moderation: People should feel incentivized to vote when they see other people around them sharing their own concerns. As soon as people perceive a certain issue to be relevant in their country, their personal-level salience – on the very same issue – should have a greater mobilizing effect. Hence, our third hypothesis considers the interaction between the individual-level mechanisms outlined above and the contextual-level issue salience.
Figure 2 visualizes the three theoretical hypotheses within our explanatory model. As laid out, we conceptualize the relevance of policy issues for electoral participation via three different theoretical arguments. First, we draw on the concept of personal issue importance and presume that the more relevant a person considers a policy issue, the more she will be motivated to make this issue visible by turning out and voting in an election (

Analytical framework and theoretical hypotheses.
Research design
To test our theoretical assumptions, we make use of two different surveys with varying scope and scale conducted during the 2019 EP election: the Eurobarometer (EB, 91.5) study and the ‘RECONNECT Europe’ (RE) panel survey. Each dataset has its own advantages. The EB integrates a set of items regarding people's
Datasets
In a first step, we examine hypotheses
In the second step, we test
Operationalization
Across the two datasets, the dependent variable in our analyses is reported electoral participation in the 2019 EP election. In both surveys, respondents were asked whether they had participated (1) or not (0) in the previous European election. Comparing the reported turnout on the aggregate level with the official numbers shows significant over-reporting in both surveys. However, while the average over-reporting is rather small in the EB (5 points), it is much larger in the RE survey (26 points). This difference possibly stems from the fact that the EB survey was carried out as a proper random sample from all member state populations, whereas the RE survey took a stratified sample from an online access panel (see the Online appendix).
The three main independent variables – personal ‘issue importance’, ‘systemic issue salience’, and ‘opinion extremity’ – are measured with slightly different yet similar indicators. Both
To measure
Individual
Apart from our main variables discussed above, we also included a series of control variables in our regression models. These comprise attitudes towards the EU and other institutions (EU support, trust in the EP, support for the national government) as well as socio-psychological dispositions (political interest, EU-specific knowledge, socio-tropic economic evaluations) and socio-demographic information (age, gender, education, social class/income). These variables account for the relevance of EU attitudes in EP elections (Blondel et al., 1998; Stockemer, 2012), but also belong to the standard determinants of electoral participation (Smets and van Ham, 2013). Moreover, the mere positions on each of the policy issues are also included as control variables in the regression models where we test opinion extremity. The reason is that the effect of opinion extremity could otherwise easily be confounded by the direction of the issue opinion, i.e., effects could be driven by only one camp of an issue dimension. Finally, to avoid omitted variable bias on the country level, we include country dummies (in fixed effects models) and the official turnout figure of the 2019 EP election (in multi-level models). 5
Empirical analysis
We estimate logistic regression models on both datasets due to the binary nature of the dependent variable (see Online appendix for the full regression results). With the EB dataset, we first compute country-fixed effects models to test the direct impact of
The Eurobarometer dataset
First, we inspect the results of the fixed effects models, which control for the influence of confounding factors on the country level. Figure 3 displays the predicted probabilities for electoral participation in function of

Predicted probabilities to participate in the 2019 EP election as a function of individual issue importance regarding three major policy issues (adjusted model predictions). (a) displays the individual-level importance of economic issues. (b) displays the individual-level importance of immigration issues. (c) displays the individual-level importance of environmental/climate change issues.
In a second step, we inspect the cross-level interactions specified in the multi-level models, expressed as conditional marginal effects of individual issue importance dependent on the

Conditional marginal effects of individual issue importance on the probability to participate in the 2019 EP election over three major policy issues. (a) displays the conditional marginal effects in the case of economic issues. (b) displays the conditional marginal effects in the case of immigration issues. (c) displays the conditional marginal effects in the case of environmental/climate change issues.
The story is straightforward regarding
The RECONNECT Europe dataset
Analyzing the RE dataset allows us to test our

Predicted probabilities to participate in the 2019 EP election as a function of opinion extremity regarding four major policy issues (adjusted model predictions). (a) displays the predicted probabilities for economic issues. (b) displays the predicted probabilities for immigration issues. (c) displays the predicted probabilities for environmental/climate change issues. (d) displays the predicted probabilities for EU integration issues.
In contrast, being strongly in favor of or in opposition to further European integration has a positive effect on electoral participation (Figure 5(d)). Therefore,
Conclusion
The surprising increase in EU-wide voter turnout in the 2019 EP election has been largely attributed to increased political conflicts over key European issues and a greater degree of politicization in these elections. Against this backdrop, we investigated whether European citizens were indeed mobilized through four major policy issues in the 2019 EP election: the economy, environment/climate change, immigration, and European integration itself. Using survey data from two different sources, we assessed our research questions from a cross-national perspective. Overall, we conclude that the four issues under investigation all played a role in mobilizing European citizens to cast a vote. More specifically, we found empirical evidence for three different effects of issue relevance.
First, the primary pathway of issue mobilization is a direct effect exerted by personal issue importance. The more relevant a person perceives key policy issues (economy, environment, and immigration), the more likely she feels incentivized to participate in European elections. On the one side, we believe that this effect speaks for the electoral impact of citizens’ political awareness more generally. The more people care about political issues, the more they strive to participate in politics. On the other side, the particularly pronounced effects of environmental and climate change issues reveal that issue mobilization is not homogeneous across all political issues. We believe that the differential effects might be a consequence of the great political urgency felt by people who worry about climate change (see also Schäfer et al., 2021b). This sense of urgency was also expressed in the ‘Fridays for Future’ movement and, subsequently, in the ‘green wave’ during the 2019 EP election in many.
Second, we observed that the impact of personal issue importance was enhanced by the systemic salience that the respective policy issues had during the election campaign. It confirmed our expectations derived from the literature on agenda-setting and the spiral of silence. People observe the ‘opinion climate’ around them and feel additional incentives to participate in EP elections when the issue they perceive as most relevant is also publicly salient in their country. In contrast, if people feel socially isolated with their personal salience attributions, they tend to stay ‘silent’ (i.e. at home) during electoral contests on the EU level. Although this finding is an important contribution to the EP election literature, it is in line with the traditional second-order model of European elections. National contexts are still highly relevant when it comes to issue mobilization during European elections.
Third, having a particularly strong or ‘extreme’ opinion on one of the three issues mentioned above (economy, climate change/environment, and immigration) has virtually no mobilizing effect in European elections. However, we have found such an effect for the EU integration issue. This observation indicates that citizens use European elections to express their views on the European integration process, which is in line with the ‘Europe matters’ model of EP elections, claiming that the consequences of European integration ‘become politically more important and more contested’ (Van der Brug and Van der Eijk, 2007: 226) in the electoral arena. Since EU issues seem to play a role in electoral participation (Braun, 2021), future studies should ultimately consider the multi-faceted nature of European issues and, for instance, distinguish between so-called EU policy and EU polity issues (Braun et al., 2016). It seems very plausible that different types of European issues have diverging electoral consequences in the EU member states. 7
What are the implications of our study for the future of EP elections and empirical research? Although we do not contest that European elections can still be considered second-order national elections, we also found evidence for their increasing politicization and the conclusion that ‘Europe matters’ in present-day EP elections (Schäfer, 2021). Moreover, our results show that the debate and electoral campaigns over crucial transnational policy issues bear the potential to increase turnout in European elections further. It might be through this process that EP elections can finally lose their second-order character and establish ‘the missing link’ between voters and parties on the European level. However, it is important to note that key political issues do not necessarily need to be explicitly related to European integration itself but can be of European-wide concern – such as environmental or economic issues. Against this backdrop, future research could investigate political actors’ potential to increase turnout via an intensified debate over transnational policy issues. Linked to this, it would be worthwhile to analyze whether actual (and perceived) competencies in specific policy areas ascribed to the EU or the national level of governance have different implications for electoral participation. Insights on these two aspects will further strengthen our knowledge on the multi-level logic of European politics and the future of European integration more generally.
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Footnotes
Declaration of conflicting interests
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References
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