Britain could leave the European Union if it fails to claw back powers from Brussels, David Cameron has suggested for the first time.
Mr Cameron said in an interview to mark the start of the Conservative Party Conference that his priority is to convince Britain to stay in a reformed European Union.
However, he added that he "wouldn't argue for us to be in it [the European Union]" if it "wasn't in Britain's interest as a country".
Philip Hammond, the Foreign Secretary, and Michael Gove, the chief whip, have both said that they would be prepared to leave Europe if Britain cannot secure the necessary reforms.
Mr Cameron said: "If I thought that it wasn't in Britain's interest to be in the European Union I wouldn't argue for us to be in it.
"I do this job because I Iove my country, I care passionately about its future and I want it to be a strong, proud, self-governing independent nation.
"Yes, working with other European countries on trade and cooperation, maximising our influence in the world. I believe we will get what we want.
"We need to get out of ever-close union, we need proper safeguards of the single market. At the heart of this yes of course there is a right to go and work in other European countries, but it is not an unqualified right. You should not be able to move for benefits or abuse the rules.
"What I believe is right for Britain is to seek reform, get reform and get Britain to vote to stay in a reformed European Union. If people don't like that plan the only way they get to vote to get out of the European Union is if I am Prime Minister.
"If I don't achieve that, it will be for the British public to decide whether to stay in or to get out." Separately yesterday it emerged that Labour has established a "convincing" 11-point lead over Conservatives in the key marginal seats Ed Miliband would need to win to secure victory in next year's general election, according to a new poll. The ComRes survey of the 40 tightest Labour/Conservative battlegrounds for ITV News comes as a further blow for Prime Minister David Cameron. Labour is at 41pc, the Tories are at 30pc, Ukip are on 17pc and the Liberal Democrats are on 6pc. (© The Daily Telegraph London)