European leaders launched a summer of wrangling over their union's political direction with a clash over nominations for Brussels' top job.

After dinner in Brussels, Germany's Chancellor Angela Merkel left saying she stood by her centre-right group's candidate to lead the European Commission for the next five years.

"We stand by our lead candidate, the EPP candidate, that is Manfred Weber. Others stand by their candidate, which is obvious," Ms Merkel told reporters.

"We have responsibility towards our voters, and we will have to wait and see. It's too early to speak about this, everyone needs to show tolerance and a willingness to engage in compromise."

But French President Emmanuel Macron said that the shifting of political balance in the European Parliament after last week's election had broken the "prison" of the candidacy process.

"The key is that the people in the most sensitive posts share in our project and are as charismatic, inventive and competent as possible," he said.

"Everyone will have to move, and we are going to have to build a consensus. In this framework the role of France, having broken out of the prison of spitzenkandidats, is to build a dynamic and credible movement, behind a project."

France - backed by progressive allies like Spanish premier Pedro Sanchez - wants a candidate who could support the programme of a broader alliance of liberal, social democratic Green and centre-right MEPs.

The president of the European Council, Donald Tusk, will now go away and try to draw up a list of nominees for top EU roles that a majority of leaders could get behind at a 21 June summit.

Angela Merkel said she stood by her centre-right group’s candidate Manfred Weber to lead the European Commission

If they fail to find consensus, the debate will drag on, as it did in 2014, when it took several summits to agree on all the top jobs.

Alongside the Commission role, the leaders also have to choose a new Council president, a foreign policy chief, a speaker for the European Parliament and a central bank director.

After the summit broke up, Mr Macron said he expected the nominations to be "even-handed - two men and two women, with a geographical balance," echoing Mr Tusk's own description of the recruitment campaign that lies ahead.

Earlier in the day, the leaders of the Greens, the socialist and the centre-right groups in parliament insisted that the leaders agree to a "spitzenkandidat" or lead candidate nominated by them to the commission.

But the centrist ALDE group, which now includes members of Mr Macron's liberal movement, refused to sign the pact, and the French leader is building support for a progressive candidate.

Mr Tusk insisted that leaders had not fallen out over names, but had instead discussed the process through which they will find names acceptable to both the 28-nation Council and the new 751-seat parliament.

Mr Weber's European People's Party (EPP) remains the biggest bloc in the European Parliament despite losing some 40 seats in the weekend election and losing the power to wield a majority in coalition with the centre-left S&D group.

But he is seen as short on charisma and has no executive experience - a fact alluded to repeatedly by Mr Macron.

As he arrived, Mr Macron insisted he did not want to talk about possible names for the job - before listing centre-left pick Frans Timmermans, EU Brexit negotiator Michel Barnier and EU Competition Commissioner Margrethe Vestager as suitable candidates, while pointedly omitting Mr Weber.

An EU source told AFP that Mr Weber could seek the presidency of the European Parliament if he fails in his Commission bid - a consolation prize not open to Ms Vestager or Mr Timmermans.

Under EU treaty law, the European Council nominates a commission president, then the parliament ratifies their choice.

But the procedure, while seemingly straightforward, masks a complex power struggle between rival states and ideological blocs and between the leaders and parliament itself.

The leaders of France, Spain, Belgium, Portugal and the Netherlands - all liberals or socialists - met over lunch and a Spanish government source said an "alliance of progressive forces" was taking form.

This could also work against the conservative Weber. Udo Bullmann, the leader of the centre-left S&D parliamentary group, said Ms Merkel was becoming "kind of nervous" as control of the process slipped from her grasp.

The EU elections saw ALDE and the Greens gain ground - ending the EPP and S&D groups' ability to form a coalition majority without their cooperation.