Veteran Cabinet minister Kenneth Clarke has warned David Cameron that pandering to the Conservatives' right-wing core support on issues like Europe and immigration risks consigning the party to "a long period in opposition".
Mr Clarke, who was made minister without portfolio in Mr Cameron's recent reshuffle, said there was electoral "danger" in trying to attract right-wing voters by aping the eurosceptic UK Independence Party, which he dismissed as "a cranky party" which had sent "a useless collection" of MEPs to Brussels.
He made clear he opposes any referendum on Britain's future relations with the European Union, which he said would be a distraction from the government's job of dealing with the economic crisis.
Speaking to a meeting hosted by The Independent on the fringe of the Conservative conference in Birmingham, Mr Clarke said: "We all dearly love our right-wing core members, and they have been part of the Conservative Party for as long as I can remember.
"But the reason we don't win elections is because we have lost a lot of people to other parties who don't come from there.
"We face serious problems. In Scotland we are in danger of going extinct, in the north of England we are very much weaker, and we have to keep an eye on the Midlands and the North. Our standing among ethnic minority voters - we need to address that.
"We need to win an election and that means... a One Nation appeal to the UK and all sections of it, remembering that we win elections when we persuade people who might otherwise have voted Labour or Liberal that we have a more broad and sensible appeal.
"If we start behaving in the way the Conservative Party has always been caricatured as behaving in the past, we resign ourselves to a long period of opposition."
Recent polls which have put Ukip at 10% or more of the popular vote have prompted discussion of whether Conservatives should contemplate an electoral pact with the eurosceptic party or take a tougher line on the European Union.
But Mr Clarke said that, while they might take a "staggering" proportion of support in European elections thanks to low turn-out and protest votes, Ukip can be expected to account for no more than 3%-4% of the vote in general elections.
"In the past, we have spent our time getting worried about Ukip while five million voters were going off to the Liberal Democrats," he said. "We helped the Liberal Democrats sweep us out of the South West by imitating Ukip.
"We have to be careful we don't give them credibility by imitating them, because they are a cranky party and they should be dealt with as a cranky fringe party.
"Trying to take them very seriously and pretending we have got to start taking on bits of their supposed policies is a danger."
Mr Clarke said he was "slightly alarmed" that the issue of Europe had returned to the forefront of Conservative debate, after years in which the party's warring wings have observed a tacit agreement not to feud over the issue, which he said "doesn't interest a high proportion of the British public".
Mr Cameron has indicated that he intends to seek the "fresh consent" of the British public to a new settlement with the EU after the general election, probably through a referendum.
But Mr Clarke said: "I don't like referendums... I think we have to be very careful about how we handle the whole question of our role in the world.
"Of course we have to negotiate exactly what the relation is between the eurozone and non-eurozone and we have to make sure that the British voice is not diminished by the fact that we are on the fringes and not in the eurozone. That is very important.
"Of course it is important to explain that to the public and get the consent of the public and democratic legitimacy for it, but we should handle this carefully.
"Whatever government is in power, to suddenly interrupt the progress of serious business in a crisis by having a whole mad campaign about whether or not we should join or leave the EU - particularly at a moment when the EU is changing - I can't think of anything more disruptive.
"Is the Government meant to be advocating a Yes vote or a No vote? Does the government resign if it loses? Or does the entire government pretend it has changed its mind and now sees the light?"
He warned: "We have more serious things to get on with, like making sure we are not marginalised in international affairs, making sure that people don't think this country has self-doubt about