Nationalist, anti-European Union parties have scored stunning victories in European Parliament elections in France and Britain, in what French Prime Minister Manuel Valls called a "political earthquake".
While the French National Front and the UK Independence Party (Ukip) finished first in their respective countries, movements opposed to closer European integration also did well in other nations.
Meanwhile, the three big centrist blocs that have traditionally dominated the European Parliament all lost seats. It was the biggest vote of no confidence in the continent's ruling elite since the launch of the EU project.
France has "shouted loud and clear", a triumphant Marine Le Pen, leader of France's National Front, told cheering supporters, that the nation wants to be run "by the French, for the French and with the French" and not by "foreign commissioners".
With most of the votes counted, her party is likely to win 24 European Parliament seats, up from just three in 2009 and way ahead of French President Francois Hollande's ruling Socialists, who were pushed into a humiliating third place.
A similar situation was seen in Britain, where Ukip captured 23 European Parliament seats, relegating Prime Minister David Cameron's Conservatives to third place after Labour.
"Our dream has now become a reality," said Ukip leader Nigel Farage of his party's victory, the first time it has won a national election.
"Up until now, European integration... always seemed to be inevitable, and I think that inevitability will end with this result tonight. I promise you this, you haven't heard the last of us."
The revolt against ruling elites was evident elsewhere in Europe. In Denmark, the People's Party, which campaigned to reinstate border controls on other European citizens and curb welfare benefits for foreigners, topped the national poll.
The far-right Freedom Party in Austria doubled its support, despite the fact that one of its candidates was recently forced to resign after calling the EU "a conglomerate of negroes".
In Hungary, Jobbik, a racist movement with its own paramilitary force, came second in the polls, with 15 per cent of the votes.
Meanwhile, Greek voters were split between extreme left- and right-wingers, while in Italy, Mr Beppe Grillo, a comedian who shouts obscenities at his opponents, came second, ahead of the party of former prime minister Silvio Berlusconi.
European elections used to be dismissed as unrepresentative of broader political trends. Turnout is traditionally low, benefiting fringe movements whose supporters are more motivated to vote.
This time, however, the European elections could have deeper consequences. For it is clear that the results represent a massive backlash against a union historically associated with growing prosperity, but now increasingly seen as the source of grinding economic austerity.
To make matters worse, today's anti-EU parties are aiming to destroy Europe's two fundamental pillars: the way the euro single currency operates, and the principle of freedom of movement for European citizens, who are currently entitled to work and settle anywhere within the union.
Flush with victory, Ms Le Pen is now trying to stitch together a block of nationalist parties inside the European Parliament. If she succeeds, this will hobble the workings of the legislature for the rest of this decade.
But even if she fails, newly elected populists are guaranteed to use their European Parliament platform for publicity stunts such as hurling abuse at ministers or EU officials.
The fear is that the more publicity extremists gain, the higher their chances of being regarded as a real political force. People who only a few weeks ago were dismissed as fringe characters could become a permanent feature of Europe's debate.
The results come as the European Parliament faces a battle over its powers.
Under treaty changes recently introduced, the Parliament's views need to be "taken into account" by the EU's national leaders when they appoint the next president of the commission, the EU's executive.
Mr Jean-Claude Juncker, the former Luxembourg prime minister and head of the centre-right alliance of political parties which is the biggest in the Parliament, has made for a pitch for the position.
However, his candidacy is expected to be opposed by countries such as Britain and France, where anti-EU sentiments now run strong and which are hardly likely to accept Mr Juncker, who is famous for advocating the creation of a "United States of Europe".
Governments may therefore opt for a compromise candidate, although this risks infuriating the Parliament, which has the power to refuse the confirmation of any appointment.
The paralysis that could ensue will be music to the ears of the newly elected nationalist parties, which argue that the continent is deaf to the opinions of its voters.
This article was first published on May 27, 2014.
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