Ken Clarke has said the Conservatives must pick a "bigger beast" than Tony Blair or Gordon Brown to ensure they defeat Labour at the next election.
The ex-chancellor was making his pitch for the job of party leader at the Conservatives' annual conference.
Mr Clarke said Mr Blair and Mr Brown were damaging democracy and he was the man to return the Tories to power.
Rival contender David Cameron, 38, said he was not too young to lead the party, and had the ideas to turn it around.
Mr Clarke, 65, said what was needed was someone voters could see as a prime minister in waiting.
The Conservatives had to win power to repair the economy, restore proper Cabinet government, Parliamentary accountability and an independent civil service, he said.
CV: Ken Clarke, 65, ex-chancellor, currently on back benches
Key Quote: "We search for leaders who will be seen by the public as prime ministers in waiting. Oh boy, have you kept me waiting."
Best joke: "David Willetts keeps telling us that we will all need to work harder and retire later. Well, Mr Willetts, sir, I will do my bit."
Ovations: 20 rounds of applause and a two minute standing ovation finale
Speech length: 23 minutes, 44 seconds
Name drops: One Thatcher, but mostly about his own record
Nick Assinder's verdict:
Self-styled 'biggest beast' says time has finally come
Mr Clarke said: "Fellow Conservatives, let us win together... I promise you if you give me the chance to lead this party, I will lead it unspun.
"I will say what I think, and try to do what I say, as I have always done in politics."
Of Mr Blair and Mr Brown he said: "We have to choose from among our number an even bigger beast than either of them to push Labour out of office at the next general election and return us to government."
He reassured Tory members that he shared their views on issues such as low taxation, strong defence, law and order and the family.
He committed himself to reintroducing the goal of limiting public spending to 40% of national wealth - 2% lower than it is at present.
He said he was the only current MP to have produced real cuts in income tax.
Mr Clarke said his party must show it was possible to have modern public services and still ensure public spending rises more slowly than economic growth.
In a broadside at the record of his successor as chancellor he said: "The tragedy is that Gordon Brown could have done great things with our inheritance.
"But he's blown it, he's blowing it now. He has turned out to be just another tax and spend Labour chancellor, but on a lucky streak."
Mr Clarke pledged to make sure Mr Brown's economic legacy haunted him if he took over from Tony Blair in 10 Downing Street.
Mr Clarke. whose pro-euro views were blamed for him finishing second in the leadership contests in 1997 and 2001, did not mention Europe in his speech, but he has insisted Europe is no longer an issue.
'Vigour and energy'
Mr Cameron, 38, is seen as competing with 65-year-old Mr Clarke for much of the same centre ground support in their leadership bids.
There has been talk of a "dream ticket" leadership team but that has been ruled out by the men themselves.
The shadow education secretary told BBC 2's Newsnight: "If you've got the right ideas in your head and passion in your heart and vigour and energy to do this job, and if... you know what needs to change in the Conservative Party, I say, 'why wait?'.
"I don't want to sit around for another four years and see us lose again." Earlier at the conference, Mr Cameron sought to make his youth a virtue by saying he wanted to change the party, to make people "feel good about being Conservatives again".
He told the conference: "I want to switch on a whole new generation to the Conservative Party," in a speech delivered without notes, before receiving a three minute standing ovation.
Mr Clarke said Mr Cameron "could be a very formidable prime ministerial candidate in a few years' time".