Why do people support the supranational delegation of authority in certain policy areas rather than others? While national identity explains general opposition to supranational institutions, support for integration varies more among policy domains than among individuals. The lack of a comprehensive theory to explain this variation limits our understanding of how coalitions for cooperation can be formed. This study posits that citizens favor transferring policies to the supranational level when they believe these policies will more closely align with their preferences compared to domestic alternatives. This hypothesis is tested through three empirical investigations focusing on policy-specific support for European integration. The first study, based on data from the 2002 European Social Survey combined with party manifestos, finds that individuals demonstrate lower policy congruence with their national governments on issues they prefer to transfer to a supranational level. The second study analyses Eurobarometer data (1989-2011) combined with a novel automated coding of the ideological orientation of EU policies, and shows that support for supranational governance is higher in areas where the EU's outputs align more closely with individual ideological stances. The third study uses a survey experiment in four countries to confirm a causal interpretation of the previous findings. These results highlight the multi-layered process through which citizens seek representation and suggest that institutional preferences are partly endogenous to policy preferences. The study advances theories of regional integration and deepens our understanding of democratic representation in multi-level governance systems.