Europeans headed to the polls in their tens of millions Sunday to choose their champions in a looming battle between the nationalist right and pro-EU forces to chart a course for the union.

Early turnout in many countries was higher than it had been five years ago, but it was not immediately clear if this was good news for the populists or for those mobilising to oppose them.

‘I guess that some marginal parties will be less marginal tonight,’ the president of the European Commission, Jean-Claude Juncker said as he cast his vote in Luxembourg.

Seven EU member states have already voted, but no official results can be published until the rest have taken part.

The European Parliament will give a voting estimate at 1815 GMT and provisional results will begin to emerge from 2100 GMT.

Eurosceptic parties opposed to the project of ever closer union hope to capture as many as a third of the seats in the 751-member assembly, disrupting the pro-integration consensus.

The far-right parties of Italian deputy PM Matteo Salvini and France's Marine Le Pen will lead this charge, and anti-EU ranks will be swelled by the Brexit Party of British populist Nigel Farage.

The president of the European Council, which represents EU national leaders, Donald Tusk said the main priority after the vote is to ‘save the EU as a project.’

France's President Emmanuel Macron has taken it upon himself to act as figurehead for the centrist and liberal parties hoping to shut the nationalists out of key EU jobs and decision-making.

‘Once again Macron is daring us to challenge him. Well let's take him at his word: On May 26, we'll challenge him in the voting booth,’ Le Pen told a rally on Friday.

It was not clear at midday which side was carrying the day, but the battle seems to have motivated French voters, with 19.26 percent turning out, 3.5 percentage points up from the same time in 2014.

Turnout was also markedly higher in Germany, Spain, Poland, Hungary and Romania, but comparable to 2104 levels in Italy.

- 'Extremists are mobilising' -

Meanwhile, the mainstream parties are vying between themselves for influence over the choice of a new generation of top EU officials, including the powerful president of the European Commission.

Turnout will be closely scrutinised in case another drop in participation undermines the credibility of the EU parliament as it seeks to establish its authority.

Britain and the Netherlands were first to vote, on Thursday, followed by Ireland and the Czech Republic on Friday with Slovakia, Malta and Latvia on Saturday, leaving the bulk of the 400 million eligible voters to join in on Sunday.

At the last EU election in 2014, Slovakia had the lowest turnout of any country, at less than 14 percent, and centrist president Andrej Kiska is worried that ‘extremists are mobilising’.

Poland's right-wing government, led by Law and Justice (PiS), has been accused of breaking European law by undermining the independence of the judiciary, but Polish voters still say they support EU membership.

‘I would like there to be no nationalists in the parliament, or at least that they do not have a majority,’ retiree Ryszard Dabrowski told AFP at a Warsaw polling station.

The right and the far-right have not had everything their own way.

In the Netherlands, the centre-left party of EU vice president Frans Timmermans won the most votes and added two seats for the Socialists and Democrats (S&D) in parliament, according to exit polls.

The S&D's centre-right rival the European People's Party (EPP) was buoyed by exit polls suggesting that Prime Minister Leo Varadkar's pro-EU Fine Gael party was in the lead in Ireland.

- Jobs fair -

Even if Britain leaves the European Union on October 31, the latest deadline for Brexit, its MEPs could still play a role in this summer's scramble to hand out top jobs.

Thursday's votes from Britain will not be counted until after polls close in Italy, but Farage's Brexit Party appears on course to send a large delegation to a parliament it wants to abolish.

Macron is pinning his hopes on joining with the liberal ALDE voting bloc and other centrist groups to give impetus to his plans for deeper EU integration.

But much will depend on who gets the top jobs: the presidencies of the Council and the Commission, the speaker of parliament, the high representative for foreign policy and director of the European Central Bank.

EU leaders have been invited to a summit on Tuesday to decide the nominees, and Germany's Chancellor Angela Merkel is expected to back the lead EPP candidate Manfred Weber for the Commission.

Macron and some others oppose both Weber, a German conservative MEP with no executive experience, and the idea that the parliament should get to choose one of its own for Brussels' prime post.