Does conflict over European integration among pro-European parties reduce public support for Eurosceptic parties?

How does conflict over European integration between pro-European parties affect the electoral support for Eurosceptic parties? In the past, pro-European parties tended to de-emphasize and blur their positions on EU affairs because of its status as a ”wedge issue” dividing their electorate and membership base (Green-Pedersen, 2012). By contrast, scholarship on the EU’s democratic deficit has long argued that a stronger emphasis on substantive policy differences within a generally pro-European frame should undermine the appeal of Eurosceptic challengers (Mair, 2007; Hix, 2013). Comparative research, too, has shown that the programmatic convergence among mainstream parties reduces turnout and strengthens anti-system parties (Grant, 2021; Spoon and Kl¨uver, 2019). In this paper, we test this link between policy-based differences among pro-European parties and public support for their Eurosceptic challengers. We field a survey experiment in five EU member states, treating respondents with different constellations of pro-EU and anti-EU party positions on EU fiscal, migration, and environmental policy and testing the link to individual support for Eurosceptic challenger parties and feelings of substantive representation. Our findings hold both theoretical and practical relevance for research on the electoral effects of mainstream party convergence and party strategies on EU affairs, respectively.