LONDON - David Cameron's failure to prevent Jean-Claude Juncker from becoming the new European Commission president risks pushing Britain out of the EU unless he builds bridges to secure reforms before a 2017 referendum, experts say.
The British prime minister suffered a serious blow to his credibility by losing his fight against Juncker, whom he believes is a roadblock to change, and Cameron admitted it made the job of keeping Britain in the European Union harder.
Many in Britain - where a long history of euroscepticism reached new heights with the victory of the anti-EU UK Independence Party in last month's European Parliament elections - currently support his stance against Juncker, who is seen by London as too much of a federalist.
Some 43 per cent of voters believe Cameron was right to try to block Juncker's appointment, against 13 per cent who said he was wrong, according to a Financial Times/Populus poll released this week.
And Cameron could still achieve the major EU reforms he wants, including repatriation of some powers, depending on how he reacts now, analysts said.
"The Juncker episode is clearly a substantial defeat for David Cameron, and without remedy, increases the risk of Brexit (a British exit from the EU)," said Mats Persson, director of the London-based think-tank Open Europe.
"However, it is far from the end of the story for sweeping European reform." British newspapers were unanimous on Saturday that Cameron's defeat had increased the risk of the country leaving the 28-nation bloc, with The Times warning on its front page, "Britain nears EU exit".
But they were divided on whether Cameron or Brussels was to blame, with several saying he was right to stand in "splendid isolation" on a matter of principle.
Persson suggested that a perceived increase in the risk of Britain leaving the EU could prompt fellow leaders to swing behind Cameron, who he added must now work harder to outline his vision of reforms in Europe.
Swedish Prime Minister Fredrik Reinfeldt, who initially showed support for Cameron's stance before eventually throwing his weight behind Juncker's nomination, said he was prepared to make an additional effort to ensure Britain's concerns were addressed.
"I'm willing to walk an extra mile to make the argument that, okay, if you dislike this it could be done in other ways," he told BBC radio.
Former defence minister Liam Fox, from Cameron's Conservative Party, insisted the defeat had not "weakened" either the premier or Britain's role in the 28-nation EU.
"The prime minister has shown Britain will not take a back-seat approach to reform of the European Union," he wrote in The Sun.
Who gets what
Key to Cameron's future situation will be who gets what as the rest of a large-scale shake-up of top EU jobs is haggled over at another summit on July 16.
Britain could be handed a key portfolio or one of its allies could take an important role such as the presidency of the European Council, the EU's political arm, currently filled by Herman Van Rompuy.
Cameron said Friday the key test for him of a candidate's suitability for a job was: "Do you get the need for reform and change in this organisation?" Ironically, his ability to drive through change ahead of the 2017 referendum on Britain's EU membership hinges on his ability to build a relationship with Juncker.
Professor Richard Whitman, of the Chatham House think-tank in London, said Cameron had no choice but to work with Juncker.
"As president of the European Commission during and after the UK's 2015 general election, Juncker's stance on the UK's relationship with the EU, the prospects and modalities of re-negotiating the terms of membership - and a possible referendum campaign - will be significant," Whitman said.
A defiant Cameron insisted Friday he was fully committed to fighting for Britain to stay in a reformed EU, regardless of how hard that is.
Simon Hix of the London School of Economics said Cameron needed to deliver on two main points - a reformed agenda for the single market and concessions on British opt-outs from certain parts of EU law.
"If he can deliver on those things, then eveyone will forget Juncker," he added.
But eurosceptics are not convinced.
"The battle over Mr Juncker was but the first skirmish in a long negotiation of a new relationship for the UK with the rest of the EU," veteran eurosceptic MP John Redwood wrote on his blog.