Another Blair government would be a danger to democracy, former BBC director general Greg Dyke has said at a Lib Dem campaign news conference.
Greg Dyke was a Labour supporter for 40 years
Mr Dyke said he had switched from Labour to the Lib Dems because he could not support a party led by Tony Blair.
Charles Kennedy said Iraq had "polluted the body politic" and that Britain would judge Mr Blair on Thursday.
Mr Blair insists he acted in good faith over Iraq. The Tories accuse him of lying over the case for the war.
Mr Dyke, who lost his job over a BBC report on the argument for the Iraq war, said it was now clear that Mr Blair and his Downing Street staff "did the same to the legal advice on the war in Iraq as they did to the intelligence".
"They chose parts that suited their case and conveniently failed to tell Parliament or the nation about the rest.
"In doing this they have undermined trust in our whole political system.
"After eight years of Mr Blair one can only conclude that our democratic system is in crisis as a result of his style of government."
Mr Dyke also likened the Labour government during the Iraq period to the Nixon Whitehouse.
"If you were a journalist and you didn't support their side, they tried to get you. If you supported them, they gave you stories.
"That's a very dangerous position for a democratic party to get into. You're either on our side, or you're the enemy."
Mr Kennedy, who toured marginal seats in the West Country, said trust in politicians had been damaged by the Iraq war.
He added that the key question for the election was the "issue of which party can be trusted with the stewardship of our country".
"The question of trust is so important, because so many of the judgements which politicians have to make have nothing to do with the promises in their manifestos."
He added that in recent days reports had shown the prime minister had decided to take military action in Iraq months before he presented any evidence before Parliament.
He also attacked Conservatives' position on the Iraq war as "utterly incoherent".
Michael Howard has said he would have gone to war in Iraq even if he had known Saddam Hussein had no banned weapons.
Mr Kennedy said: "First they were the principal cheerleaders for war. Since then they have tacked and flip-flopped, desperate to wring some political advantage out of the situation."
The Lib Dem leader also resisted suggestions that a vote for the Lib Dems was a vote for left-wing policies.
Mr Kennedy says if you vote Lib Dem you get Lib Dem
He told BBC Radio 4's Today programme: "I am not pushing this party to the left, I am pushing this party forward."
He also claimed many voters who had supported the Conservatives in the past were worried about issues the Lib Dems wanted to tackle, such as ageing parents, student fees and council tax.
"There is a lot of people who have voted for other political parties in the past looking at us and looking at us in a very positive way."
The party's election chief, Lord Razzall, launched a further attack on Labour claims that a vote for Lib Dems would let in Mr Howard by the back door.
"For him to have an overall majority, you have to have a swing of over 15% and even that presupposes that all goes from Labour to Tory."