Most people expect a "grand coalition" of the centre-right European People's Party and the Socialists to form, controlling over 400 seats out of 751 in the EU assembly to ensure business as usual, but this could fuel further euroscepticism.
In Britain, Prime Minister David Cameron said: "The results show a very clear message, which is people are deeply disillusioned with the EU, with the way that it's working, with the way that it's working for Britain, and they want change. The challenge is now for my party to demonstrate that we have the plan to deliver that change: to renegotiate Britain's place in Europe; to get a better deal for Britain; to change Europe."
In Greece, Golden Dawn, a neo-Nazi party whose leaders are in jail on criminal charges, overtook the Panhellenic Socialists, a pillar of the European establishment that oversaw their country's transition to democracy from a right-wing military dictatorship.
Syriza, a far-left party opposed to the eurozone's programme to stop Greece defaulting on its debt, won the European elections with a substantial lead and could trigger meltdown of the EU single currency if it succeeds in its demand for national elections.
Hollande held a crisis Cabinet meeting to find ways to overcome what is the French Socialist Party's worst showing since the first European elections were held in 1979.
The Front National clinched almost 25 per cent of the vote, quadrupling its 2009 score in what its leader, Marine Le Pen, said was a "massive rejection" of the EU.
"We are witnessing the total rejection of the system," she told Le Monde yesterday. "This is a kind of patriotic revolution" pitting the FN against the two main political parties, the Socialists and the opposition centre-right UMP. "The split is now between nativists and globalists."
Despite its strong showing, the FN was engaged in frantic moves to secure an alliance with anti-EU groups from seven different countries - the minimum required to form a parliamentary group. Believed to be a couple of countries short, Le Pen was thought to be trying to woo allies of Nigel Farage's UKIP to form a pan-European anti-EU group.
Left and right with a joint agenda
Is the bloc's implosion just a matter of time?
Marine Le Pen and other Eurosceptic leaders have said they want to bring down the EU from the inside. But despite the rhetoric from Le Pen and UKIP's Nigel Farage, pro-European forces still dominate the 751-seat Parliament. The centre-right European People's Party has a projected 213 seats, and the Socialists and Democrats group has 190. With 117 seats between the Liberals and Greens, there is a clear majority of moderates.
Who exactly are these fringe parties that have made the gains?
They cover a wide political spectrum from far left to far right. Currently there are seven recognised political groups in the Parliament: the four mainstream pro-European parties, a hard-left grouping and two Eurosceptic alliances. UKIP and the far-right Danish People's Party sit with one of the anti-EU groups. Parties on the far left, such as Syriza in Greece, are part of the hard-left group, where Sinn Fein's three new MEPs will also sit. There are many parties that have MEPs for the first time. These include those with neo-Nazi traits, such as Greece's Golden Dawn and the German radical National Democratic Party. On the far left, Italy's anti-establishment Five Star Movement will have its first seats. Spain also saw a proliferation of smaller parties. You also have more established populist parties, such as the Front National and Geert Wilders' Freedom Party in the Netherlands.
Are all these far-right parties going to join together into a supergroup?
That's the plan of Le Pen and Wilders, who want to form a new official political group in the Parliament, which means more influence. They need at least 25 MEPs from seven member states. So far the Austrian Freedom Party, the Belgian Vlaams Belang, the Swedish Democrats and Italy's Northern League have suggested they will join. They only need one more party. The hard right is, however, beset with divisions.
Is the result so catastrophic that it will bring down any governments?
There have been serious blows for ruling parties across the EU. In Greece, the far-left Syriza party won the vote, pushing Prime Minister Antonis Samaras' New Democracy into second place. Denmark's ruling party was also pushed into second place by populists, this time on the far right, with the anti-immigration Danish People's Party getting four seats compared with three for the governing party.
- Independent