Donald Tusk (left), Juri Ratas and Andrej Babis attend a round table at the European Union leaders summit in Brussels. Reuters

Sleep-deprived European Union leaders adjourned marathon talks until on Tuesday amid stalemate over filling the bloc's top jobs in the wake of May elections that have fragmented the EU political landscape.

The 28 EU leaders are trying to agree on who will steer the bloc over the coming years through the looming challenges of Brexit and the rise of populist parties in Europe.

Despite 18 hours of talks since Sunday, they needed more time to debate new proposals to overcome opposition to a Franco-German compromise on who will be the new chief of the European Commission, the bloc's executive arm.

European Council (EUCO) President Donald Tusk "suspends the meeting and reconvenes #EUCO tomorrow at 11h," tweeted Tusk's spokesman Preben Aamann.

Summit organiser Tusk had suggested in vain to French President Emmanuel Macron and German Chancellor Angela Merkel around 8am (0600 GMT) to drop efforts for now and reconvene in two weeks, a European source told AFP.

"The two replied to him: 'It's out of the question. We must absolutely find a deal today,'" the source said on condition of anonymity.

The compromise Merkel and Macron forged on the sidelines of the G20 summit in Japan on Saturday called for Dutch Social Democrat Frans Timmermans to head the commission, rather than his conservative rival German Manfred Weber.

French President Emmanuel Macron leaves a EU leaders summit in Brussels on Monday. Francois Lenoir/Reuters

Weber would instead be put forward for election as speaker of the European Parliament, where he leads the largest political bloc. A liberal candidate would succeed Tusk as president of the European Council of national leaders.

But when Merkel put this to fellow centre-right leaders in the European People's Party (EPP) several rebelled, and the summit was thrown into crisis as heads of government shuttled between side meetings late into Monday morning.

Merkel said later Monday she still "hoped that with good will a compromise will be feasible."

The EPP is still the biggest bloc in the European Parliament, but no longer the dominant force it was before the May elections.

The liberals, which include Macron supporters, and Greens are increasingly assertive trying to choose the top jobs after they made huge gains in those elections.

Even though the Social Democrat bloc also lost ground, Timmermans, the commission's current vice president, emerged as a compromise candidate to head the powerful commission.

Germany's Chancellor Angela Merkel arrives for an European Council Summit in Brussels. Kenzo Tribouillard/AFP

"There is a strong consensus for Timmermans but the situation is very volatile. I'm more optimistic than I was three hours ago," another European source said.

The latest idea is to have Timmermans head the commission, and the EPP's Kristalina Georgieva, a Bulgarian, heading the European Council, several European sources told the media.

They also want a liberal as the diplomatic chief to replace outgoing commissioner Federica Mogherini of Italy. That could either be Belgian prime minister Charles Michel or Danish politician Margrethe Vestager, who currently oversees anti-trust policy on the commission.

Another source said Vestager could serve as vice president of the commission.

Agence France-Presse