The Tories said a backlash from Europe "won't make a difference" today as David Cameron was accused by a leading French minister of "castrating" Britain's influence in Brussels.
The Conservative leader yesterday promised to try to wrest back powers from the European Union after ditching his pledge to hold a referendum on the Lisbon Treaty.
He also vowed to change the law so that no further powers could be lost to the EU without a UK referendum.
But his positioning drew charges that he was pandering to the strongly eurosceptic wing of his party and provoked angry criticism from a member of France's centre-right government.
Pierre Lellouche, the French minister for Europe, told The Guardian that Mr Cameron's plans would marginalise Britain in continental affairs.
"It's pathetic. It's just very sad to see Britain, so important in Europe, just cutting itself out from the rest and disappearing from the radar map," he said.
But shadow foreign secretary William Hague told BBC Breakfast the party would take criticism "in our stride".
Mr Hague said: "I think more senior members of the French Government would take a more careful approach. We take that in our stride.
"Will we we get back a bit of abuse for it? Yes, but that won't make a difference."
Mr Lellouche said the Tories had a "bizarre autism " on the EU and likened their latest moves to their withdrawal from the main centre-right grouping in the European Parliament.
"They are doing what they have done in the European Parliament," he said. "They have essentially castrated your UK influence in the European Parliament."
He also insisted there was no chance of European leaders helping the Tories re-negotiate powers at this stage.
"It's not going to happen for a minute," he said. "Nobody is going to indulge in rewriting (treaties for) many, many years.
"Nobody is going to play with the institutions again. It's going to be take it or leave it, and they should be honest and say that."
Mr Cameron said yesterday that it was pointless to hold a referendum on the Lisbon Treaty now that all 27 European Union members have signed the document.
He said he did not want to "rush into a massive Euro-bust-up".
But he also sought to quell Tory anger at the U-turn by proposing what he called a "referendum lock" on the further transfer of powers to the EU.
He said he would seek to negotiate the return of powers in areas of social and employment legislation and criminal justice, and a complete opt-out from the Charter of Fundamental Rights.
And he proposed a United Kingdom Sovereignty Bill to make explicit, in the absence of a written British constitution, that ultimate authority remains with the Westminster Parliament.
In an illustration of the difficulty of his position however, the Tory leader is also facing backbench demands to go further and pledge a referendum on Britain's relationship with the EU.
Eurosceptic Conservative MP Douglas Carswell insisted that such a referendum was essential.
"I fully accept that a referendum on Lisbon may no longer be possible, but nobody under the age of 52 has ever had the chance to vote on our membership and our relationship," he said.
"It's changed quite dramatically since we joined.
Last night, Eurosceptic Conservative MEP Daniel Hannan quit as European legal spokesman in protest at his party's stance on the Lisbon Treaty.
Announcing his resignation on his Telegraph blog, Mr Hannan said he would return to the back benches to campaign for "a broad movement within the Conservative Party that will push for referendums, citizens' initiatives and the rest of the paraphernalia of direct democracy".
In a letter to The Sun newspaper explaining his position, Mr Cameron said: "I did not promise a referendum come what may because once the Lisbon Treaty is the law, there's nothing anyone can do about it. And I'm not going to treat people like fools and offer a referendum that has no effect.
"What I am promising today is do-able, credible, deliverable - giving the British people a policy on Europe they can actually believe in."
He insisted: "Never again should it be possible for a British government to transfer power to the EU without the say of the British people."