The two men hoping to succeed Sir Menzies Campbell as Liberal Democrat leader have clashed over the retention of Britain's nuclear deterrent.
Mr Huhne and Mr Clegg laid out their stalls at hustings in London.
Following hustings in central London, Chris Huhne said he would dump the Trident missile programme.
Nick Clegg argued that such a move would destroy the UK's bargaining power in non-proliferation talks in 2010.
Mr Clegg is backed by 27 Lib Dem MPs, while Mr Huhne has 10. The party's 70,000 members have the final vote.
The leadership race was sparked two weeks ago by the sudden resignation of Sir Menzies, who blamed ageism for his decision to quit.
Ballot papers will be sent out to party members on 21 November, with the new leader unveiled on 17 December.
But during the first of 10 hustings in the leadership race, Mr Huhne said the UK should get rid of Trident altogether.
"You cannot properly equip our soldiers in Iraq and Afghanistan and spend 20 billions pounds on replacing Trident. We must back our troops and not Trident," he said.
However, Mr Clegg hit back that there was little point attending the next non-proliferation talks in 2010 if "we've already thrown all our cards away".
"We've got to bring the Trident deterrent down to the absolute minimum and use the remaining capability to act responsibly and multi-laterally, not only to disarm ourselves but the world too," he said.
Kicking off his hustings speech, Mr Clegg stressed that the contest was a "great opportunity" for the Lib Dems to overcome what had been a "slightly rocky period in our party's history in the last couple of years".
He said the Lib Dems needed to become an "outward facing party again", reaching out to the millions of voters who "share our values for fairness, social compassion, internationalism, the wish to protect the environment".
"Third place is just not good enough," he said. "That's why I'm determined, if I lead this party, that we should break the stale old grip of tired two-party politics within a decade."
He said it was possible that Lib Dems could secure 150 seats within two elections - the party currently has 63 MPs.
"It might be the Liberal Democrat members who decide this contest, but it's the British people who are listening," he said, adding that the party should re-establish its "anti-establishment credentials".
He offered to lead a "people's campaign" against ID card legislation, adding that he was prepared to be hauled before the courts.
In his pitch, Mr Huhne said he did not want to become "the heir to Blair or David Cameron's stunt double".
He accused Gordon Brown and Mr Cameron of being "crass, callow and conservative".
"Frankly there are already two Conservative parties in British politics and we don't need a third. What Britain needs is a radical party," he said.
In his manifesto launch he promised a "people's veto" over unpopular legislation, with a public referendum on new laws if enough people are opposed to them within a period of up to 100 days of their passage through Parliament.
He suggested that the number of voters needed to spark a referendum should be 2.5% of the population.
Mr Huhne said he would match Mr Clegg's promise to lead a campaign against ID card legislation, pointing out that he had long promoted civil liberties.
"I don't think it's right that a government with 35% of the vote has a legitimate mandate to impose something so unpopular and corrosive to traditional freedoms in Britain as ID cards," he said.