LONDON (Reuters) – Prime Minister David Cameron has privately conceded he may have to campaign for Britain to leave the European Union if he continues to be “completely ignored” by EU partners, The Daily Telegraph reported on Saturday.

Citing an unnamed source, the newspaper said Cameron has made clear to senior figures in his party that he will lead the “Out” campaign in a planned referendum if he considers the result of his renegotiation with Brussels to be unsuccessful.

“He has said that if he is completely ignored, or if they give him nothing, he will campaign to leave” the Telegraph’s source said.

“It’s not something he wants to do, but in recent weeks he’s made it clear it’s no longer impossible.”

The newspaper also cites Downing Street officials as saying they have calculated that the prospects of Britain staying in the EU are only “marginally better than 50 per cent.”

The newspaper report will add to the pressure on other members of the 28-nation bloc to accommodate Cameron’s demands.

Cameron is seeking to renegotiate the terms of Britain’s EU membership and says he wants to stay in a reformed EU. However, he says he rules nothing out if he can’t get change on matters such as limiting EU migrants’ access to welfare payments.

European Council President Donald Tusk said on Thursday that a discussion with Cameron at an EU summit this month should pave the way for a deal in February, opening up the possibility of a referendum from around mid-year.

Tusk, who is leading the EU negotiations with Britain, also wrote on Twitter that he would send a letter to national leaders on Monday with his assessment of the British negotiations.

A spokesman for the prime minister said his approach had not changed.

“The Prime Minister’s position is absolutely clear. He is confident he can get a good deal for Britain from these negotiations, which will allow him to campaign for the British people to vote to remain in a reformed EU,” said the spokesman.

“But he has always said that if we cannot get the deal Britain needs, he rules nothing out.”

Separately on Saturday a report in the Financial Times said Cameron’s push to rebrand the EU as a “multicurrency union” has triggered high-level concerns at the European Central Bank, which fears it could give countries such as Poland an excuse to stay out of the euro.

The FT cites an unnamed British official as saying ECB president Mario Draghi “is worried that people would resist harmonisation by arguing that the UK and others were gaining an unfair advantage.”

(Reporting by James Davey; Editing by Keith Weir)