Get off the fence and back EU referendum, Cameron taunts Clegg ahead of landmark vote later this week Prime Minister rounded on his deputy ahead of a landmark vote this week Warned that the public won't be satisfied with a stay-away policy on the EU The Lib Dems dismissed the move as a "parliamentary stunt" and vowed to boycott it By Tim Shipman And Jason Groves The Coalition was at war over Europe last night as David Cameron taunted Nick Clegg to "get off the fence" and back an in-out referendum. The Prime Minister rounded on his deputy ahead of a landmark vote this week in which Tory MPs will back legislation for a nationwide poll by the end of 2017. As the Lib Dems dismissed the move as a "parliamentary stunt" and vowed to boycott it, Mr Cameron warned that the public will not be satisfied with a stay-away policy on an issue of such potent concern to voters. David Cameron has taunted Nick Clegg to 'get off the fence' on the issue of an EU referendum "In the end, people have to get off the fence," he said. I totally support it. It is my policy written into law. And I would say to all MPs, turn up and vote. Mr Cameron, who is on a tour of Asia, taunted Mr Clegg for previously backing an in-out referendum but then refusing to back a Bill proposed by the Tory MP James Wharton which would give the public a say. Lib Dem Cabinet minister Danny Alexander dismissed the vote as a "Parliamentary stunt" and accused Mr Cameron of conjuring up a referendum "for domestic political reasons." Nick Clegg previously backed in in-out EU referendum, but then refused to support a later bill Condemning the Prime Minister's entire European strategy, he said the Tories should concentrate instead on making a positive case for the UK staying in the EU. Mr Alexander, who accused Mr Cameron of "wasting our influence" by trying to repatriate powers from Brussels, confirmed the Lib Dems would join Labour in boycotting Friday's Commons vote on the Referendum Bill. "I think this is a sort of parliamentary stunt," he said. We are not going to be there. He dismissed the threat from the UK Independence Party, saying: "Ukip will come and Ukip will go but what matters is Britain stays a full member of the European Union." Meanwhile, Lib Dem Business Secretary Vince Cable will today set out the case for Britain staying in the EU. Speaking at an event organised by pro-EU cross-party group British Influence, Mr Cable will say leaving is "neither a good nor a realistic economic option." Mr Cameron has imposed a three-line whip on his MPs. With most Labour and Lib Dem MPs abstaining, the Bill is almost certain to get its second reading in the Commons on Friday. He has had to back a private members" bill because Lib Dem opposition to a referendum means he cannot introduce government legislation. Piling pressure on Mr Clegg, Mr Cameron pointed out that it was Lib Dem policy at the last election to back an in-out referendum. The Prime Minister said: "The Liberal Democrats, like everyone else, have to make up their mind: do they want to give the British people a say or do they not? If you go back to their manifesto, it's quite like what their policy used to be and who knows, maybe it can be once again. Ed Miliband is expected to get his MPs and peers to derail the Bill in its committee stage and in the House of Lords The row threatens to undermine a bid by Mr Clegg today to put on a united front with the Tories and turn his fire on Labour over the economy. Mr Clegg will dismiss claims the Coalition is "running out of steam," adding: "Labour, on the other hand, are incapable of making a single decision. I think I preferred it when Labour stuck to their monastic vow of silence on the economy - when they tell you what they think it's extraordinarily difficult to follow. Ed Miliband is expected to get his MPs and peers to derail the Bill in its committee stage and in the House of Lords. But the Labour leader is under growing pressure from his MPs to back a referendum, with at least ten members of the Shadow Cabinet privately arguing that opposing it shows contempt for and fear of the voters.