De rol van EU-beleid bij het vormgeven van EU-steun: een transversale en longitudinale analyse van beleidscongruentie en publieke opinie in de Europese Unie

Whilst a plethora of discussions proliferate regarding democratic output legitimacy, surprisingly little research has devoted efforts understanding whether institutional policy packages adequately represent the will of the people and whether this reflects in variations of political attitudes among the public. Such investigations are even more limited at the European Union (EU) level, where the second-order nature of European Parliament's (EP) elections, citizens' indifference towards the European political arena and lack of data on EU policymaking challenge the possibility of drawing ultimate conclusions on the influence of EU policy outcomes on public opinion. For this reason, the thesis explored the research question: "To what extent is EU public support affected by the policies that the EU enforces?". To answer this question, the author posits that public views on European integration are not the mere result of subjective evaluations of EU's general performance or of simplistic cost-benefit calculations of the EU membership, but rather rely on the congruence between citizens' policy positions and the enacted policy. More specifically, public support for the EU is expected to increase as the alignment between citizens' policy preferences and the actual policies enacted by the EU grows. From a theory perspective, the present thesis addressed this research question of policy-opinion relationship by linking three strands of literature: studies on national and European representation, on EU public attitudes, and on EU legitimation. The interdependent nature of these academic fields allowed the author to provide a thorough picture of the relationship between input, throughput, and output factors and public attitudes towards the European Union. To support this theoretical framework, the project employed two original datasets: a cross-sectional multilevel dataset covering 28 EU member states, and a longitudinal data frame considering the Netherlands, spanning policies of four European parliamentary legislatures across 20 years, from 2004 until 2024. The two data strands are the result of several linking strategies between the EP roll-call vote data retrieved from VoteWatch Europe and the individual-level data gathered from the European Election Study (EES) and the LISS Panel respectively. While EES and LISS studies provide most of the variables used in the analysis at the individual-level, VoteWatch Europe data are essential to calculate the EP- and country-party positions on EU enacted legislation, necessary estimates to compute policy congruence at the individual level. Furthermore, the employment of both cross-sectional and longitudinal data allows to test this relationship across and within countries, providing cross-country comparisons and trends over time within member states. Leveraging the work invested in assembling the final datasets, the project dedicates the first part to the operationalization of congruence estimates conducted on the EP roll-call vote data, the distribution of party sympathy levels of EES and LISS respondents, and the descriptive statistics of the two final datasets. This summary statistics is later complemented by the inferential analysis. Here, the author carries out a regression analysis with multilevel and fixed-effects models for the cross-sectional EP-EES, and fixed-effects and random effects models for the longitudinal EP-LISS dataset. Additionally, ordered logistic regressions have been included as a robustness check for those dependent variables that are ordinal in nature. The findings demonstrate that higher levels of policy congruence significantly and positively predict citizen support for EU institutions, effect that remains consistent across policy domains. This pattern holds for all cross-sectional models for both dimensions of support and across all longitudinal models for specific support, while for diffuse support under the panel study it emerges only in the random-effects and ordered logit specifications. Contrary to the dissertation's expectations, policy congruence was observed to have a significantly higher impact on the diffuse dimension of EU support than the specific aspect, although under the longitudinal dataset this finding is observed only for random effects specifications. These trends apply to findings for the whole EU, the country groups of Western and Eastern Europe, and for the Netherlands as a case study. Furthermore, in line with the thesis' assumptions, the impact of congruence on public support for the EU in Central-Eastern Europe is comparatively higher than the West. This confirms the theoretical argument that Central-Eastern Europeans are able to gauge the benefits of European integration substantively more than Western older democracies, identifying policy congruence when available by holding the authoritarian past as a benchmark. Furthermore, the congruence-support relationship is found to be moderated upon political interest for those with medium and high levels of political curiosity, whereas education does not seem to play any moderating role. This finding applies to the EU as a whole, and the West and the East groupings. Considering the Dutch case study, both education and political interest appear relevant only under random effects models. Lastly, the results show that support is slightly more influenced by congruence on more recent legislation, albeit this evidence is inconsistent across models and specifications, suggesting further investigation is needed. By integrating theories of democratic legitimacy, representation, and public attitudes, building an original dataset linking EU elites and public behavior, and introducing policy congruence as an innovative methodology to assess EU-level policy-voter linkages, this dissertation makes a substantive contribution to our understanding of how EU decisions and governance affect political support. It challenges the assumption that citizens are disconnected from EU policymaking, showing on the contrary that Europeans are responsive to the content of EU policies and form stable attitudinal judgments towards these policies based on policy alignment. These findings have important implications for debates on the EU's democratic deficit and for designing mechanisms to improve institutional legitimacy and citizen engagement in the European integration project.