David Cameron’s bid to block Jean-Claude Juncker becoming the next European Commission president looks set to fail after his allies changed tack.
German Chancellor Angela Merkel had given the British prime minister hope after agreeing to a vote on the issue if there was no consensus.
But both the Netherlands and Sweden now say they will back Luxembourg’s ex-PM.
Mr Cameron says Mr Juncker’s nomination ignores the “pro-reform message” sent by European voters last month.
The EU summit starts on Thursday after leaders first commemorate the 100th anniversary of the start of the First World War in Ypres.
That ceremony will be followed by a working dinner on the EU’s long-term policy agenda in Brussels, before EU leaders make a decision on the Commission presidency on Friday.
Mr Cameron has said he will demand an unprecedented vote if Mr Juncker’s name is tabled so that EU leaders are forced to justify their support for the veteran politician in public.
The UK prime minister believes Mr Juncker is too much in favour of closer political union and might block reform of the EU.
He also objects to the idea that EU leaders are allowing the European Parliament to effectively make the choice, since Mr Juncker was the leading candidate of the centre-right group that topped May’s polls.
The UK’s Europe minister David Lidington said choosing the Commission president from among those leading candidates risked making the EU executive a “creature of the European Parliament”.
Previously, the job at the head of Commission has only been given with the unanimous agreement of at least the EU’s bigger countries, including Britain.
But with Hungary’s Prime Minister Viktor Orban now Mr Cameron’s only supporter, correspondents say Mr Juncker is likely to be overwhelmingly backed as the nomination, even if it does go to a vote.
Chancellor Merkel said on Wednesday that it would be “no tragedy” if Mr Juncker won the Commission’s top job with less than unanimous backing.
But Downing Street said that she later agreed with the British PM that a vote should take place if necessary.
A statement from No 10 said she also underlined their support for Britain’s continued membership of a reformed EU.
But the BBC’s Chris Morris says the fact that such a statement needs to be made is a reminder of how damaging this row has become.
Speaking in Berlin on Tuesday, Mr Juncker said he expected to be confirmed as the next Commission president by the end of the week “if common sense prevails”.