David Cameron's dramatic decision to play his last hand with a bill promising a EU referendum in 2017 appears to have done little to quell disturbance in the Tory ranks, as rebel Tories reiterated plans to push ahead with a vote on an amendment to the Queen's speech.
The PM is to publish a draft Bill for an EU referendum, but is unable to put it forward as legislation himself as the Government can do nothing to bind future parliaments.
Instead, Cameron has to hope it will be tabled by a backbencher as a Private Member's Bill.
Many Tories have called on backbenchers to back the plan.
But it may not prevent an embarrassing backbench rebellion after 78 MPs declared their support for an amendment tabled by John Baron and Peter Bone which says it "respectfully regrets" that there was no room in the Queen's Speech for legislation on an EU referendum.
Baron said that, although the move by No 10 was a "step in the right direction", it was a "second-best offer" and he will continue to press for support for his amendment.
"I think this is a once-in-a-lifetime opportunity in many respects," he told the BBC Radio 4 Today programme. "The Prime Minister should seize the moment presented by our amendment.
"He can legitimately say to the Liberals that the situation is not of his making and therefore not within the confines of the Coalition Agreement."
"This is not a matter of trust between David Cameron and the Conservative Party - it's a matter of trust between politicians and the electorate."
"If we can win the vote on Wednesday, the Prime Minister can go to the Deputy Prime Minister and say Parliament has spoken, we must introduce this as a Government Bill."
Is my party going mad? What can I say on The Daily Politics today? Psychiatrist needed, not political commentator.— Matthew Parris (@MatthewParris3) May 14, 2013
Foreign Secretary William Hague said the move would force Labour and the Lib Dems to "show their hand" whether they are prepared to match the Conservatives' promise of an in/out referendum on Europe.
"When the dust settles on all the speculation about Europe over the last few days, what is clear is that the Conservative Party is solidly committed and very united behind that commitment to a referendum in the next Parliament, and other parties have either set their face against that or, in some cases, their MPs are now saying they ought to contemplate a referendum.
"They will now have to show their hand."
The Foreign Secretary said that the draft Bill would show that "even though we can't pass legislation as the Government in this Parliament, we really do mean to have that referendum by the end of 2017 after seeking a new settlement with the European Union".
And he added: "We had a range of options. We would have done this or some other similar option because we do want to reinforce our commitment. The Prime Minister said before the local elections, before the Ukip local election results, that we were looking for ways of doing that and open to ways of doing that.
"I think it's the right thing to do for the country. Holding a referendum after seeking a new settlement in Europe would be the right thing to do for the country, so, since we are putting that forward, let other people now say what their position is."
The bill also went down like a lead balloon with the opposition party, including the Eurosceptic UK Independence Party.
Ukip leader Nigel Farage said in a statement that the bill was a reaction to a surge in support for his party, now at a record high.
"This is clearly a Prime Minister not in control and a Government in total disarray. It is a basic principle of our democracy that no Parliament can bind a successor, without the support of Parliament this is a meaningless piece of constitutional shadow play."
A senior Lib Dem source said the issue of an EU referendum law was not discussed during coalition negotiations on the Queen's Speech and Cameron's move was prompted by "internal Tory trauma".