Even if most voters see European Parliament elections as an opportunity to register a protest vote, the results of the May 22-25 ballot should be troubling to Europe's mainstream parties. The outcome of that vote is a wakeup call to Europe's establishment. They must re-examine fundamental assumptions about the role of the European Union and how they talk about the European project at home.

The EU cannot be used as a scapegoat for domestic woes, a way to dodge hard domestic decisions, without undermining its legitimacy. Europe is still struggling with the effects of the economic downturn triggered by the 2007-2008 global financial crisis. Recoveries have been fitful and uneven, and the prospect of contagion — in which one weak economy on the continent pulls others down with it — is very real.

While Europe's most solid economies are angry at being asked to subsidize the so-called profligacy of less responsible states, those suffering states complain that they are being forced to endure austerity to prop up the banks of their well-to-do neighbors.