David Cameron has vowed to mount a fresh attempt to enshrine in law his commitment to stage an in-out referendum on Britain's European Union membership after a backbench Tory bill was effectively killed off by Labour and Lib Dem peers.
The Prime Minister said he wanted to see a new bill introduced in the next session of parliament and would, if necessary, use the Parliament Act - which limits the power of the Lords to block legislation - to ensure it gets on the statute book.
His comments were dismissed as "a bit of bluster" by his Liberal Democrat coalition partners who made clear that they had not been consulted and would continue to oppose the legislation.
Earlier Mr Cameron's plans to re-negotiate the terms of Britain's membership ahead of a referendum after the next general election received a further setback when French president Francois Hollande made clear he was not interested in changing EU treaties.
Following the Anglo-French summit at RAF Brize Norton, Mr Hollande told a joint news conference that while he wanted to see Britain remain a member of the EU, re-opening negotiations on the treaties was not a "priority" for Paris.
In the House of Lords, Labour and Lib Dem peers combined to ensure the EU (Referendum) Bill would make no further progress, with peers voting by 180 to 130 to end debate without completing its committee stage.
Tory backbencher James Wharton, who had brought forward the legislation as a private member's bill at the behest of the party leadership, said: "Labour and the Lib Dems have conspired in the House of Lords to kill this important piece of legislation, doing the bidding of their political masters in the Commons."
Although Mr Cameron is committed to holding a referendum if the Conservatives are in power after the next general election, Tory Euro-sceptics have been determined to keep up the pressure by writing it into law.
It would also mean that if a future Labour government decided not to go ahead with the referendum, it would have to stage a vote in Parliament to repeal the legislation.
Any new bill would again have to be introduced as a private member's bill as the Lib Dems are not prepared to give it Government time in making progress through Parliament.
In a letter to Tory activists, Mr Cameron said the defeat in the Lords was "disappointing" but he was determined not to give up on the legislation.
"After all, we succeeded in passing it through the House of Commons - a huge achievement," he said.
"We are going to try to reintroduce the same bill in the next session of Parliament and, if necessary, rely on the provisions in the Parliament Act to stop Labour and Liberal Democrat peers killing the bill once again."
His comments were dismissed by the Lib Dems who suggested that he was simply playing to his own MPs and activists.
"This sounds like a bit of bluster after the rather unedifying events of yesterday," a spokesman said in a reference to an Immigration Bill vote that saw the Prime Minister duck out of a confrontation with rebellious backbenchers.
"There hasn't been any discussion with us about this. We don't agree with this bill and we are not going to change our position just because the Tories have problems handling their backbenchers and are running scared of Ukip."
For Labour, shadow foreign secretary Douglas Alexander said it would be an "unprecedented" move for Mr Cameron to try to force through a major constitutional initiative by means of a private member's bill.
"The House of Lords today has once again raised serious questions about the Prime Minister's approach towards such a serious constitutional matter," he said.
"The truth is that this bill has always been more about Tory Party management than Britain's national interest."