Nick Clegg has accused David Cameron of allowing greater uncertainty to hit the British economy by cultivating hopes of a referendum on the EU.
Ahead of a key speech from the prime minister on Friday, the Liberal Democrat leader said the clamour for an in-or-out referendum was having a "chilling effect" on growth.
"I do not think we should do anything to jeopardise our leadership [in Europe] and we certainly should not do anything which would have a chilling effect on jobs in this country," Clegg told the Today programme.
"We should be very careful at a time when the British economy is still haltingly recovering from the worst economic shock in a generation to create a very high degree and a prolonged period of uncertainty because in my view uncertainty is the enemy of growth and jobs and our priority, in this government and in the national duty, has got to be to foster growth and jobs."
Clegg, who is a committed europhile, warned that pulling out of EU justice measures would hit anti-terrorism and crime efforts, despite expectations that Cameron will highlight problems with the European arrest warrant.
The deputy prime minister's comments hint at the battle of wills in Downing Street at Cameron's much-hyped European speech.
The prime minister is expected to offer a referendum to voters after renegotiation of powers in Brussels but several obstacles stand in his way – not least winning a Commons majority and getting European states to agree to the negotiations while they have their hands full with the eurozone crisis.
The interview was badly received online, after Clegg seemed to claim that Lib Dem promises of an in-or-out EU referendum in the 2010 general election were not really policies, despite their presence on election leaflets.