David Cameron was under intense pressure last night to give voters a say on reforming the European Union as he ditched his pledge of a referendum on the Lisbon treaty.

After the Czech President dashed Conservative hopes by signing the accord, Eurosceptics urged Mr Cameron to back up his promise to try to repatriate powers with the threat of a referendum.

It was unclear yesterday whether the Tory leader would go as far as that when he sets out his new policy on Europe this afternoon. He will pledge to renegotiate Britain’s relationship in some areas and says that he will legislate to prevent any future European constitutional treaty going through without a referendum in Britain.

Members of Mr Cameron’s Shadow Cabinet fear that a threat to hold a referendum on the results of a renegotiation could swiftly turn into a vote on whether Britain should remain in the EU — something both he and they want to avoid. Worse than that, they believe that a referendum called about a year after the general election could become a public vote on a Conservative government’s performance.

Mr Cameron is likely to say that he will seek to claw back powers from Brussels in three areas: foreign policy, employment legislation, and justice and home affairs. The details on the measures and the timing of their “repatriation” are unlikely to be spelt out.

The Tory leader has denied that abandoning his pledge of a Lisbon referndum is a betrayal, arguing that it applied to the treaty. By the time the Conservatives could take office, after a likely spring election, it would not be a treaty but part of European law.

William Hague, the Shadow Foreign Secretary, sounded the death knell of the Tory campaign for a Lisbon referendum soon after Václav Klaus, the Czech President, became the last EU leader to sign the treaty. He said: “The people of Ireland have had two opportunities to vote but the British people have never even voted once, and we will not let people forget whose responsibility that is.”

But Conservative Eurosceptic MPs urged Mr Cameron to put his proposals for taking back powers from Brussels to a popular vote.

Philip Davies, Conservative MP for Shipley, said: “It is important to have a referendum so that David Cameron can go to Brussels and say, ‘This isn’t something I’m demanding, this is something that the British public is demanding’.”

David Davis, the former Shadow Home Secretary, said that Mr Cameron had “an unenviable task” but said that there should be “a referendum, not on the treaty, but on the negotiating mandate that the British Government takes to the European Union”.

He said that this would allow the public to express their view on the subject and, more importantly, would act as “a formidable negotiating weapon”.

“Referendums terrify the European Commission and ther political elites who run Europe. They are clear statements of the popular will,” he wrote in the Daily Mail.

He said the referendum should cover several strategic aims such as recovering control over criminal justice, asylum and immigration policies, an opt-out of the European Charter of Fundamental Rights and a recovery of rights to negotiate on trade.

David Miliband accused Mr Cameron of taking a “false and dangerous” stance on the Lisbon treaty that risked Britain’s national interests.

“The fact is, you can’t simply opt out of treaty obligations because to do so you need the agreement of the 26 other member states. The concessions David Cameron would have to offer would be costly and weaken Britain considerably,” he said.

It has emerged that Lord Turner of Ecchinswell, the chairman of the Financial Services Authority, is a candidate to become Britain’s next commissioner. He could be proposed as internal market commissioner if Britain secures neither the EU president nor the foreign minister roles, senior government sources told The Times.

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