Cameron's 'party of change' attempts to woo Lib Dems

"If you want to have a more family-friendly, greener Britain, a more liberal Britain, then the people who can get that done in government are the Conservatives," he said.

"I hope that all people who want these things – some of which were set out today by the Liberal Democrats – come with us in the modern Conservative Party and we can get it done."

He hailed the Liberal Democrats' description of Labour's planned National Insurance rise as a "damaging tax on jobs" as a vindication of his party's pledge to scrap it – though Nick Clegg's party fell short of making such a promise.

As he returned to the campaign trail after yesterday's Tory manifesto launch, Mr Cameron also launched an attack on Gordon Brown after the Prime Minister admitted failing to be tough enough in regulating banks when he was Chancellor had been a mistake. Mr Cameron claimed it was an admission that the economic problems were actually created by him and not international forces.

Mr Cameron resumed campaigning ahead of today's head-to-head confrontation between the trio in the first of the unprecedented live televised leader debates.

Mr Cameron again admitted yesterday that he was nervous about the debate.