Deputy Prime Minister Nick Clegg has issued a warning to the Tories to concentrate on fighting the “firestorm” in the eurozone rather than trying to re-negotiate Britain's membership of the European Union.
As David Cameron prepares to deliver a keynote speech in the new year setting out his vision of Britain's future in the EU, the Liberal Democrat leader said the UK should have the confidence to take the lead in Europe.
The Prime Minister is widely expected to demand a repatriation of powers from Brussels as the price of agreeing financial reform of the eurozone, with the promise of a referendum of the 2015 general election.
But in an interview with The Guardian, Mr Clegg insisted that talk of a referendum was premature and amounted to no more than "political shadow boxing".
"What we really should be doing is just focusing on the kind of economic firestorm at hand, working co-operatively to help them to put out the fire in the eurozone and to come out of this phase of economic emergency," he said.
"I think to have a referendum, kind of about nothing very much in particular, when you're in the middle of an emergency repair job to your own economy and European economy, is putting the cart before the horse.
"It's an exercise of political shadow boxing to try and anticipate a process of which we're not one of the principal authors and then start now prescribing how we should react to it."
Mr Clegg said past prime ministers from Margaret Thatcher to Tony Blair had offered "extraordinary leadership" in the EU, and that Britain should once again put itself at the forefront of developments.
"At every point when there's been a fork in the road about whether Britain should retreat or lead, when we have led we have always surprised ourselves and others about how successfully we can lead," he said.
"It short changes us as a country to assume always that we cannot lead when all the evidence is, throughout our history, even if we're not in the centre of the action that's going on across the Channel, that we nonetheless can bring great leadership to bear."
Shadow foreign secretary Douglas Alexander said: "Even the Deputy Prime Minister now recognises this Tory-led Government's failures on Europe. But rather than talking about them, he should take responsibility for the fact that the Government he and David Cameron lead is more focused on leaving the EU than leading it.
"Instead of negotiating with European partners, David Cameron still seems to be spending his time negotiating with his own backbenchers.
"Rather than a narrow agenda of repatriation, the Prime Minister should be advancing a broad agenda of reform to negotiate a deal that is good for Europe and best for Britain."
Mr Alexander later dismissed a call from a Labour former cabinet minister for Ed Miliband to call a referendum on UK membership of the EU, to be held six months after the 2015 general election.
Writing in The Guardian, pro-European Shaun Woodward said that an in/out referendum "may now be the only way to drain the poison from our membership".
But Mr Alexander told BBC Radio 4's World at One: "With the greatest of respect to Shaun Woodward, he has never been a central figure in Labour's discussions about European issues.
"Our policy remains unchanged. We don't think we could or should make a decision in relation to a referendum when the overwhelming challenge, that not just Britain faces, is to secure growth, and the challenge Europe faces is to secure the recovery of the eurozone.
"We believe clearly and categorically that Britain's future lies within the EU and rather than spending our time speculating about exit from Europe, we should be concentrating on securing reform in Europe.
"That's what I wish the Prime Minister was spending his time doing. The reason he has delayed his speech for more than a year is not that he doesn't have talented speech-writers, it is that he doesn't know what to say."