The stage has been set for a parliamentary clash between the coalition parties over Europe, after David Cameron pledged to back a Conservative MP's bill to pave the way for a referendum on Britain's membership of the EU.
After coming top of the annual ballot for Private Member's Bills, Stockton South MP James Wharton will put forward legislation drafted by the Conservative Party leadership, which would require a national referendum by the end of 2017 on the question: "Do you think that the United Kingdom should remain a member of the European Union?"
The move was branded "self-indulgent" by Liberal Democrat Business Secretary Vince Cable, who warned it would do "serious damage" to the UK economy by creating uncertainty among potential international investors. Liberal Democrats are refusing to allow government time to be used on the backbench legislation.
But the Prime Minister was said to be "very pleased" by Mr Wharton's decision and pledged to do "everything we can" to bring the EU referendum bill to a vote - including by imposing a three-line whip on Tory MPs.
The whipping arrangements could mean that any Tory ministers who fail to vote for the referendum will face the sack, potentially putting europhile Cabinet minister Kenneth Clarke in an awkward position.
Labour said it will not support the bill, but declined to say whether its MPs will be whipped. "The principle is we do not support committing now to an in/out referendum," said a senior Labour source. "We will consider the tactical question when it comes up, but we do not want it to go through. "
Mr Wharton, who at 29 is the youngest Conservative MP, said that it was "about time that this issue was tackled head-on in Parliament".
He added: "The Conservative Party has committed to holding a referendum by the end of 2017 and I believe Parliament should be given a chance to show its support for the Prime Minister's position and enshrine this commitment in law. I will be bringing forward a bill to give people a say on our membership and hope that MPs from across the political divide will support me."
Mr Wharton's bill will be presented to the House of Commons on June 19 and the earliest date he can request a full debate is July 5.
Private Member's Bills are vulnerable to filibustering by opponents, and many fail through lack of parliamentary time, so there is no guarantee that it will reach the statute book - particularly as the bulk of Labour and Liberal Democrat MPs are expected to oppose it.