Liberal Democrat leadership hopefuls Nick Clegg and Chris Huhne have set out their rival pitches in the first head-to-head hustings of the campaign.
Chris Huhne and Nick Clegg are battling for votes
Mr Clegg pledged to go after Tory leader David Cameron and "demolish" his vision of liberal Conservatism.
Mr Huhne promised a broadside against the prime minister and argued that huge investment in the schools and NHS has not been matched by results.
The two were battling for votes in the first of 10 regional gatherings.
The environment, social justice, civil liberties and the economy featured in the speeches of both men to the party faithful in Rugby, Warwickshire.
Both also underlined the need for "ambition" in the party to break Britain's two-party system.
Mr Clegg, the party's home affairs spokesman, attacked Labour's record on social mobility and said taking on the Tory leader would be his number one priority.
"I'm going to set about demolishing this idea of a liberal Conservative put about by David Cameron," he declared.
"One of my first tasks as leader would be to cast the spotlight very, very strongly on Cameron saying 'if you are a liberal why are you leading a party which is so illiberal?'"
Mr Huhne, the party's environment spokesman, identified global warming as the central issue "not merely of this campaign, but of my life".
He also branded Britain's £20bn commitment to Trident nuclear missiles "unacceptable" when troops lacked basic kit.
Mr Huhne mocked Gordon Brown as "the patron saint of tax accountants" and said nobody had seen real improvements in the NHS or education.
Mr Clegg is the bookies' favourite and frontrunner at Westminster after submitting nomination papers signed by 28 of the Lib Dem's 63 MPs - almost triple the 10 nominations secured by his rival.
The contest will be decided by a ballot of the party's entire membership, but the figures suggest a strong preference for Mr Clegg among the MPs the winner will lead at Westminster.
Ballots will be sent out in mid-November to members and the victor announced in mid-December.