Europe Tory Row Dogs Cameron's US Trip David Cameron has defended his approach to the EU and issued a thinly-veiled rebuke to Tory ministers who said they would currently vote for Britain to leave. The Prime Minister, speaking on the way to the US, tried to play down a new Tory row over Europe, claiming some people were "slightly over-excited." Asked whether he still had control of his party, he dismissed talk about how senior Tories would vote if a referendum was held now as "hypothetical." And he insisted all Tory Cabinet ministers were united behind the plan to fight for a better deal with Brussels and then hold a public vote by 2017. "I think we are all confident of the success," he declared. The idea of throwing in the towel before the negotiations even started, I think, is a very very strange opinion. Mr Cameron also defended giving backbenchers a free vote on a Commons amendment criticising the absence of a referendum Bill in the Queen's Speech. He argued that letting Tory ministers abstain in the potential vote on Wednesday while MPs are allowed to back the motion is a "sensible approach." Michael Gove (L) and Philip Hammond say they would vote for an exit now The Prime Minister's comments came as he travelled to Washington to push for an EU-US trade deal at talks with Barack Obama. Pressure over Europe has gathered pace in the wake of the UK Independence Party's strong showing in the local elections earlier this month. The Tory right has been galvanised by party grandees including ex-chancellor Lord Lawson and former defence secretary Michael Portillo calling for an exit. On Sunday, Education Secretary Michael Gove and Defence Secretary Philip Hammond both said they would vote to leave the EU if a vote was held now. Another seven senior Tories are reported to privately agree with the pair. Mr Cameron had hoped to settle party divisions over Europe with his pledge in January to hold an in-out referendum by 2017 if the Tories remain in power. But there is now concern that his plans do not go far enough, prompting MPs to call for legislation in this Parliament to guarantee a referendum in the next. Up to 100 Tory MPs could back the amendment criticising the lack of a rerendum Bill in the Queen's Speech in this week's vote. Downing Street has told ministers to abstain but is allowing other MPs, including parliamentary aides, a free vote and Mr Cameron is said to be "relaxed" about the result. Boris Johnson said on Monday that he supports legislation to back an EU referendum bill but also warned that quitting the Union would not solve Britain's problems. Boris Johnson backs the call for legislation to ensure a referendum The Mayor of London, tipped as a future Tory leader, pledged his "full support" to Mr Cameron's strategy to seek a new deal with Brussels and then stage a referendum by 2017. But he warned that negotiations would only work if other countries were clear Britain could walk away completely if the PM fails to achieve the changes he wants. And he said he wanted to see legislation now "to make sure that referendum goes ahead" because it would force a proper debate here about Britain's position. "We will all have to focus not on the feud - so toxic, so delicious, so gloriously fratricidal - but on what is actually right for the country; on the nuts and bolts of what we are trying to achieve," he said. We are all going to have to wrap that cold towel round our heads and ask: do I want in or out? And why?" he said. Former Tory foreign secretary Sir Malcolm Rifkind warned backbenchers they were putting Mr Cameron in an "impossible situation" because the amendment would not be passed. "The motion cannot win because there is not a parliamentary majority for it..." he told the BBC. All those supporting it will have achieved - they will have split their own party, they will have cast questions over the Prime Minister's authority, and indirectly, unintentionally, they will be helping the Labour Party's prospects at the next general election. That is not just foolish, it is quite contrary to all the political instincts of a responsible political party that wants to hold and retain power after the next general election.