David Cameron could take the extraordinary step of voting against his own Queen's Speech next week, as he attempts to placate Tory eurosceptics who want to see a referendum on EU membership as soon as possible.
The prime minister has promised to hold an 'in or out' referendum should he win the next election. But Conservatives who want him to pass legislation before 2015 that would enshrine the commitment in law and plan to try and amend the Queen's Speech to reflect this.
And on Friday it was suggested Cameron would actually join his backbenchers in voting against his own legislative programme. A Downing Street source told The Sun: "This amendment backs up his policy, which is a Conservative Party policy, so why shouldn't he vote for it too."
On Thursday the prime minister's spokesperson said Cameron was "relaxed" about the prospect of Tory MPs, including ministers, organising to vote in favour of an amendment tabled by Conservative John Baron.
By suggesting he would vote against the Queen's Speech, David Cameron is signalling to his backbenches that the only thing preventing him legislating for a referendum before 2015 is Nick Clegg and the Liberal Democrats in government.
The Lib Dems are opposed to holding a referendum on EU membership, arguing the uncertainty it would cause would damage the UK economy at a time it remains vulnerable.
Cameron's plan to renegotiate a looser relationship with Brussels before putting that new settlement to the British public has come under intense pressure this week.
Former Tory chancellor Lord Lawson has said he expects him to fail and said he would vote for Britain to leave the EU immediately, as has former Tory defence minister Michael Portillo.
Boris Johnson, flirting with eurosceptic Tory backbenchers, repeated his claim today that the UK should be "prepared" to pull out of the EU. "I don't think it would be anything like as cataclysmic as is being sometimes pretended," he said.
Cameron could however be saved from having to choose between voting for the amendment (and against his own legislative agenda) or against it while several Tory MPs defy him - as he may be on an official trip to the United States when it comes up for a vote.
Any amendment calling for legislation to bind the next government to holding a referendum would likely be defeated as both the Lib Dems and the Labour Party are opposed to the idea.
However one Labour Big Beast has come out in favour of exiting the EU. Denis Healey, a former Labour chancellor, has joined the calls for the UK to exit the EU.
He told Channel 4 News: "The advantages of being members of the union are not obvious. The disadvantages are very obvious. I can see the case for leaving – the case for leaving is stronger than for staying in.”