BRUSSELS -- European Union leaders went into an 18th consecutive hour of negotiations on Monday in a tortured search for a candidate to fill the post of European Commission president after all-night talks led to an impasse.

With German Chancellor Angela Merkel unable to corral her allies into supporting a deal with France and Spain, European Council President Donald Tusk tested names with small groups of leaders throughout the night.

But even after dawn broke and the 28 leaders went for breakfast, the early frontrunner Dutch socialist Frans Timmermans was unable to command a majority as eastern Europeans and Merkel’s center-right European People’s Party rebelled.

“At the moment there is no agreement,” Italy’s Prime Minister Giuseppe Conte told reporters just before the breakfast session got underway in the glass and steel Europa building in Brussels.

The summit is a third attempt to fill five top posts running the European Union for at least the next five years, forging policy for the world’s biggest free-trade area and more than 500 million people.

Leaders had hoped to first agree on a name to replace Jean-Claude Juncker as EU chief executive that would then allow a deal on who should replace Mario Draghi as European Central Bank president.

But that decision will almost certainly be postponed as leaders try and break the deadlock of the Commission chief.

Photographs taken by diplomats during the night showed French President Emmanuel Macron seated with his centrist political allies from Portugal, Spain, the Netherlands and Belgium as they sought ways to convince others to back Timmermans, a former Dutch foreign minister.

Under a deal between France, Germany, the Netherlands and Spain hatched on the sidelines of the G20 summit in Japan last week, Timmermans would run the Commission and the EPP would take the European Parliament presidency for their candidate, German EU lawmaker Manfred Weber.

The impasse underlines broader decision-making problems facing the EU, which has struggled to respond to a series of crises in recent years, from migration to climate change and the aftermath of the global financial crisis.

The EPP rebellion also underlined how weakened German Chancellor Angela Merkel, whose Christian Democrat party belongs to the group, has become as she prepares to handover to her successor.

A second European official described her as being in a “very weak moment”, struggling to control her party and with much scrutiny of her health after suffering two episodes of shaking in public.

The EPP is the largest group in the EU parliament though it does not have a majority.

“The vast majority of EPP prime ministers don’t believe that we should give up the presidency quite so easily,” Ireland’s center-right Prime Minister Leo Varadkar told reporters. Bulgarian Prime Minister Boyko Borissov said: “Merkel is the chairman of the CDU, not the EPP.”

‘Bizarre'’ selection process

But Merkel, Macron and Spanish Prime Minister Pedro Sanchez said they too were not giving up without a fight.

“Merkel and Macron are not going home without a decision,” said one European diplomat, saying the nature of the talks had echoes of Britain’s as yet unsuccessful attempts to leave the European Union because few leaders knew what they want.

“They only say who they don’t want in the Commission post.”

To be appointed, the next Commission president needs the support of at least 72% of the 28 member states, who must represent at least 65% of the EU population.

Diplomats said getting names agreed was crucial for the EU’s standing, as more delays would only provide fodder to anti-establishment nationalists who say the bloc is out of touch with its citizens, divided and dysfunctional.

But seeking a fair gender balance and a range of candidates from both eastern and western Europe is proving a challenge, while leaders had hoped to avoid a series of back-room deals by being more transparent.

“Still no white smoke,” Dutch liberal EU lawmaker Sophie in’t Veld said on Twitter. “No other major democracy in the world has such a bizarre and arcane method for choosing its political leadership.”

Female candidates for the Commission include Danish liberal Margrethe Vestager; Kristalina Georgieva, the Bulgarian head of the World Bank for EU foreign affairs chief; and Christine Lagarde as ECB president, diplomats said.