The anti-EU surge shows the European Union has got "too big and too bossy", said British Prime Minister David Cameron on arriving for an informal summit due to take stock of the election disaster.
The vote "is a clear message that we cannot just shrug off... And carry on as before," he added.
"The EU has got too big, too bossy, too interfering and needs to concentrate on growth and jobs."
Also on the leaders' dinner menu -- and perhaps just as difficult to digest -- will be tough talks on the nomination of new leaders for the different Brussels bureaucracies, in particular the presidency of the powerful European Commission.
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Germany's Angela Merkel and Hungary's Viktor Orban stepped into the talks, however, publicly differing over their support for the candidate elected by the European Parliament conservatives -- ex-Luxembourg premier Jean-Claude Juncker.
The four-day European Parliament election that ended Sunday served up a clear message of voters fed up with economic distress, belt-tightening austerity, immigration and, most of all, aloof and meddlesome bureaucrats in Brussels.
After decades of striving to tighten EU integration with "more Europe", many Europeans seem to believe that is no longer the answer.
Cameron, who has one eye on national elections next year, saw anti-EU outsider -- the UK Independence Party (UKIP) -- make history by topping polls in Britain.
In contrast to Cameron and Hollande, Merkel came out of the Parliament elections relatively unscathed, delivering her usual message of the need for "growth and jobs... The best answer" to the EU's current malaise.