David Cameron is under growing pressure to defy his Liberal Democrat coalition partners and stage a referendum on Europe before the next General Election.
Senior Conservatives urged the Prime Minister to hold a “mandate referendum” on his plan to re-negotiate the terms of Britain's EU membership as early as next spring in a bid to halt the rise of Nigel Farage's rampant Ukip.
David Davis MP said they should put it to a Commons vote and challenge Labour and their coalition partners the Lib Dems to vote against it.
“It would be very interesting for the Liberals — and indeed the Labour Party — to vote against giving the public a say on this matter,” he told the BBC1 Sunday Politics programme.
He said staging the poll to coincide with the elections to the European Parliament next May would be “an absolute Ukip killer”.
Foreign Secretary William Hague also did not rule out putting it to a Commons vote.