Cameron promises to seek 'fresh consent' of Britons over EU I think that will provide, over time, opportunities for a new settlement between Britain and Europe. And when we achieve that settlement, we will be able to seek fresh consent from the British people. Some Conservatives, including Cabinet ministers, want a clear and public promise that Britain's relationship with the EU to be put to the electorate in a referendum. Despite hinting at sympathy with that call, Mr Cameron has repeatedly declined to promise a referendum, which would raise the prospect of a British exit from the union. Asked if seeking "fresh consent" would definitely mean a referendum on Europe, Mr Cameron again declined to promise a public vote. "A new settlement and a fresh consent from the British people, that is what I believe we need," he said. He also suggested that any consultation on Europe will have to wait until after the next election, due in 2015. "In the next Parliament, I think there will be opportunities for a fresh settlement and for new consent to that settlement," he said. Previously, Mr Cameron has suggested that public approval on European issues can be obtained either through a Parliamentary vote or at a general election. Mr Cameron has said that he believes Britain should remain a member of the EU, arguing that being in the union is in the UK's economic interests. Speaking in Rio de Janeiro, he restated his commitment to membership. I argue for Britain's membership because I want to be able to say to countries like Brazil `Come to Britain and you can sell to the 320 million consumers across Europe. I argue for Britain's membership because I think it is in our interests. If I didn't think it was in our interests, I wouldn't argue for British membership. In a separate development, it emerged that the Prime Minister has responded to a group of eurosceptic MPs who wrote to him three months ago demanding legislation before the next general election, due in 2015, to pave the way for a referendum soon afterwards. Extracts of the letter, signed by more than 100 backbench Conservatives and organised by MP John Baron, were obtained by the Spectator magazine. They show that Mr Cameron has not ruled out a referendum at some point in the future, but does not believe in committing to holding one on a set date. The Prime Minister wrote: "I do believe it would be wrong to rule out any type of referendum for the future. However, I am concerned that making a legal commitment now to hold a referendum in the next Parliament without setting the exact referendum question would not be a workable, nor a sustainable, position. Mr Baron described Mr Cameron's response as a "step forward," adding: "You need to read it twice as it is very carefully constructed, but the bottom line is that he's saying Europe is going through radical range, let's see the results of our concerted effort to get a fresh deal. It's a step forward because up to this point he hasn't talked about getting the consent of the British people. But Stewart Jackson, who resigned as a ministerial aide in order to vote against the Government over Europe, told the Spectator that Mr Cameron risked losing voters to Ukip unless he gave an unequivocal promise to hold a referendum. "Voters don't trust politicians who try to sell nuanced convoluted issues with the implicit assumption that they're too stupid to understand the big issues," he added. David Cameron has an opportunity very soon to show leadership by committing unequivocally to an in/out EU referendum. Without it, Ukip will wreck any chance of an overall majority for the Conservative party in 2015.