The winner is set to be announced on 2 March

Sir Menzies Campbell, Simon Hughes and Chris Huhne addressed the audience of more than 1,000 people in London.

They each spoke at the Euston meeting, hoping to win party members' backing with just six days left to vote.

The leader to replace Charles Kennedy will be announced on 2 March, the day before the party's spring conference. It will end a month of campaigning.

Mr Huhne, 51, who has emerged as the favourite to win, said Britain deserved a modern Liberal Democrat government.

'Principles and ideas'

"We have the principles and ideas and passion and energy and talent to put Liberal Democratic principles into power," he said.

He also called for honesty about taxation. "Fair taxes, green taxes, but not higher taxes," he said.

Sir Menzies Campbell, 64, told the audience he would be an experienced, credible and campaigning leader.

The North East Fife MP said the party should move from "mere survival" to political power.

He said of Chancellor Gordon Brown and Tory leader David Cameron: "The ground they want to occupy is our ground.

"When it comes to individual freedom and personal liberties, we know about these issues."

Mr Hughes, 54, told party members he would be a leader of "reason and principle".

He said: "Our role will not be to drive around in ministerial limos, but to use our power and influence for policies and laws that bring about a truly liberal, enlightened and decentralised Britain."

The three candidates have travelled around the UK facing audiences in areas including Edinburgh, Cardiff and Manchester during an arduous campaign .

The 73,000 Lib Dem members will vote by postal ballot.