Deputy Prime Minister Nick Clegg delivered a fresh warning to Tory Eurosceptics today not to leave Britain isolated in the EU.
The Liberal Democrat leader said demands from Conservatives in the coalition for the repatriation of powers from Brussels could cost jobs and growth in the UK.
He accused Eurosceptics of a headlong rush down "a cul-de-sac of increasingly arcane legalistic arguments" about changes to EU treaties which may never actually happen.
"Isolation costs jobs, costs growth, costs people's livelihoods," he told BBC Radio 4's Today programme.
"That is why people need to be careful what they wish for, because if you wilfully move to the margins of Europe, before you know it you will find that it is actually hitting people where it hurts most in terms of their jobs and their livelihoods, and that is not something I think anybody should seriously want."
Mr Clegg said the "urgent, overriding national priority" for the whole coalition should be to promote jobs and growth.
"We do that by being in the centre of the argument, not on the outer fringes of the argument in Europe," he said.
"If instead we rush headlong down a cul-de-sac of increasingly arcane, legalistic arguments about changes to treaties that may or may not be open to renegotiation in the future, then I think that would be a form of displacement activity from our overriding national duty.
"We have got to get the best out of the European Union, not seek to get out of the European Union.
"The last thing we should do is betray our own history and our own traditions by turning inwards and isolating ourselves from the outside world."