Nick Clegg says EU referendum not in UK interest

He launched a renewed assault on his coalition partner as opinion polls suggested the Tories had enjoyed a bounce from the long-awaited policy.

Mr Cameron said he wanted to stay in the EU but pledged to claw back powers and offer voters a choice of a new relationship or exit by the end of 2017 if the Conservatives are returned to power in 2015.

It has delighted eurosceptic backbenchers fearful of the challenge of the UK Independence Party, which slipped in the latest polls.

Mr Clegg dismissed the prospects of securing a significant renegotiation, and suggested Mr Cameron should be concentrating on the economy – which risks a triple-dip recession.

“My priority will always remain a simple objective of building a stronger economy in a fairer society, enabling everybody to get on in life,” the Liberal Democrat leader said.

“And I think that job is made more difficult if you have years and years of tying yourself up in knots having arcane debates about the precise terms of the membership of the European Union before we get to a referendum.

“It is not in the national interest when we have this fragile recovery, when we have a very open economy which is very dependent on investors in the car industry and the banking system and so on.

“You must always, when you are trying to piece together a recovery, foster those precarious conditions of greater confidence in the economy – you mustn’t do anything to make that more difficult.”

He denied his party had done a U-turn by opposing a referendum – having argued for an in-out vote in 2008 – saying that had been in the context of the approval of the Lisbon Treaty.

Mr Clegg again declined to say whether he would form a coalition with the Tories if there was no clear winner at the 2015 general election.

Labour leader Ed Miliband again defended his decision to oppose the referendum promised by the Prime Minister.

“I just don’t think it’s in the national interest. Right now, it doesn’t make sense to commit to a referendum years ahead.”

One poll, by ComRes, put the Tories on 33 per cent, with Labour unchanged at 39 per cent and the Liberal Democrats up two at 11 per cent.

The poll found a majority of voters backed Labour and Lib Dem warnings that Mr Cameron’s position would cause “years of uncertainty which will be bad for the British economy” by 43 per cent to 30 per cent.

However, a majority also now believes that leaving the EU would in itself be bad for the economy in terms of lost jobs and trade – by 38 per cent to 36 per cent, a turnaround from November when 40 per cent disagreed and 36 per cent agreed.

Another poll, by Survation, put the Tories up two at 31 per cent, Labour stable at 38 per cent, Ukip down two to 14 per cent and the Lib Dems down one at 10 per cent.

Meanwhile, former prime minister Tony Blair issued a rallying cry to the “sensible, solid majority” in favour of membership to start campaigning for a “yes” vote.

The UK leaving the EU would be an “extraordinary denial of its own interests”, he wrote.