Tory Eurosceptics press David Cameron to campaign 'Out' at EU referendum after 'humiliation' over Juncker appointment

Despite his political failure in Brussels, the Prime Minister received a hero’s welcome from Tory MPs

Cameron at the EU summit last week: he was doomed to try and fail in his mission to block the appointment of Juncker (EPA)

Conservative Eurosceptics today piled pressure on David Cameron to argue for Britain to quit the EU following his failure to block Jean-Claude Juncker’s nomination as European Commission president.

They lined up to praise the Prime Minister’s lonely opposition to the federalist’s appointment, saying it should be a springboard for Mr Cameron to take a tough stance in his attempt to renegotiate the terms of Britain’s EU membership.

Despite the diplomatic disaster in which he was outvoted by 26-2 at last week’s EU summit, Mr Cameron received a hero’s welcome from Tory MPs when he made a Commons statement on the meeting.

Mr Cameron has previously insisted he intends to secure a new deal for Britain and would then argue for an “in” vote in the in/out referendum he has promised by the end of 2017. But on Monday he adopted a more neutral tone over the position he would take in the referendum, telling MPs he would act in the national interest.

He was asked by the Clacton MP Douglas Carswell: “What would have to happen for you to come back from your renegotiations and recommend people vote ‘out’?” Mr Cameron replied: “I think it is in the national interest to renegotiate our position in Europe, to secure the changes I have set out. I don’t start the negotiations believing we won’t achieve those things, I set out wanting to achieve them… but I will always do what is in the national interest.”

David Nuttall, another Eurosceptic, said: “Many millions of British people want a relationship based on trade and co-operation and if the rest of the European Union do not agree it would be no surprise if the British people vote to leave the EU?”

Mr Cameron replied: “Ultimately this is going to be a choice for the British people. My job is to make sure we secure the very best renegotiation so that people who want to stay in a reformed EU, who believe it’s in our national interest to do so, get the best possible choice.”

Julian Lewis, Tory MP for New Forest East, asked: “Isn’t there something to be said for having an obvious and overt federalist as Commission president rather than a covert and rather cleverer alternative?”

Mr Cameron said Britain would have to deal “open and frankly” with Mr Juncker, pointing to his promise to address Britain’s call for reform of the EU. The Prime Minister added: “We now need to make sure we hold him to that.”

Mr Cameron clashed with Ed Miliband, who told him: “Your party may think it represents splendid isolation - it isn't. It is utter humiliation." He said Mr Cameron's strategy of using "threats, insults and disengagement" was "a masterclass in how to alienate your allies and lose the argument for Britain".

The Prime Minister accused the Labour leader of being “weak, opportunistic and wrong.” He told him: “ I won't take lectures on negotiation from the people [Labour] who gave away the veto, who gave away the rebate, who backed down on the budget every year, and who even signed us up to euro bailouts.”

Lord Mandelson, the former Labour Cabinet minister and European Commissioner, urged Mr Cameron to “stop waving round the threat of a referendum in Britain as if it’s some sort of pistol we are holding to everyone’s head and saying ‘you’ve got to agree with us or else.’ ”

Charles Kennedy, the former Liberal Democrat leader, told Mr Cameron he could have enjoyed “influence in private instead of impotence in public” if he had not pulled Tory MEPs out of the centre-right European People’s Party in 2009.