Former deputy prime minister Lord Heseltine has given David Cameron his backing in the Conservative party leadership contest.
Lord Heseltine says David Cameron has an "elusive quality"
Lord Heseltine, who had previously supported Kenneth Clarke in the race, said the 39-year-old had an "elusive quality that encapsulates people".
Mr Clarke has again refused to say who he is endorsing for the top post.
Mr Cameron, meanwhile, says the party needs to recognise Labour's efforts and respond to a new era in politics.
The Conservatives must stop feeling as if the voters got it wrong at the last three elections and cannot assume the "pendulum will swing back", he said.
"It hasn't all been a disaster," he told the Daily Telegraph.
"We can't turn the clock back to 1997 and pretend it has all been a bad dream."
Mr Cameron and David Davis are battling for the votes of 300,000 party members.
Mr Cameron said: "There is an attitude among some that all the Conservative Party has to do is to shout a bit louder and hate modern Britain a bit more and everyone will come rushing to the standard - and I just think that is not part of the problem; that is the problem."
Mr Davis kicked off his campaign on Friday with a visit to Warwick University, where he was a student.
Asked what the difference was between himself and Mr Cameron, Mr Davis said: "David Cameron gives a lot more emphasis to the reform of the party. I give a lot more emphasis to the reform of the country."
Lord Heseltine had previously talked of a Kenneth Clarke-David Cameron "dream ticket".
But he is now supporting Mr Cameron and has dismissed suggestions that the old Etonian was "too posh" to lead the party back to power.
Mr Cameron's "ability to communicate with the wider public is part of his appeal", he told BBC Radio 4's Today programme.
"Within the Conservative party we have made a terrible mistake in allowing ourselves to be driven from the centre ground," he said.
"David Cameron is going to recapture it and, indeed, in a sense Cameron is the message."
Liam Fox, who was knocked out of the leadership race on Thursday, says he has not decided if he will publicly declare who he is going to vote for.
In an interview with the BBC, Mr Clarke suggested Conservative MPs who brought his third leadership bid to an end are out of touch with voters.
It was the third time the ex-chancellor had run for leader
"One problem that troubled me was my discussions with MPs were not the kind of discussions I would have with real people," he told BBC Radio 4's The Week in Westminster.
It is thought Eurosceptic MPs voted tactically to ensure Mr Clarke's elimination because of his pro-Europe views but the former chancellor said it was "blindingly obvious" Europe was not a major current issue in British politics.
"I'm not remotely resentful about the fact that people didn't vote for me," Mr Clarke said.
"But I'm stilled dogged by this one curiosity of all my leadership campaigns that my colleagues do seem to me to want to go on about Europe rather more than is healthy and rather more than I do actually."