In the two decades since the emergence of the European Union at Maastricht there has been a concerted attempt to build a European political space, typified by the debates on constitutionalization and democratization. Much less noticed, but no less important, has been the mobilization of publics, interest groups and political parties against the integration process. In the light of the failure to realize the Laeken objectives, the stabilization of an anti‐integration bloc in the European Parliament, recurrent ‘no’ votes in national referendums and the emergence of an increasingly co‐ordinated movement of critical interest groups, it is argued in this article that this opposition has become embedded and persistent, at both European and national levels. This will have considerable consequences for the Union itself and the way it has chosen to largely ignore sceptical voices to date.