Michael Howard has launched a further direct attack on the Prime Minister today, shrugging off accusations that he is dragging the election campaign into a personality war.

The Tory leader, who in an interview with The Times today bluntly described Tony Blair as a "liar", reinforced his assault on Mr Blair's integrity, accusing him of "eight years of broken promises." He urged voters at a rally in Edinburgh to tell the Prime Minister "where to get off" on May 5.

Last night, the Conservatives unveiled their latest poster campaign, accusing Mr Blair of being "prepared to lie" to win the election, just as he had over the Iraq war.

Alan Milburn, Labour's election co-ordinator, said that the Tories are trying to hijack democracy through negative campaigning because they calculated they would benefit from a low turnout and have deliberately sought to depress the vote.

He told BBC Radio 4’s Today programme: "This is an election about turnout. The worry for us is that propensity to vote among Conservative voters seems to be higher than the propensity to vote among Labour voters.

"That plays very much to the Conservative strategy. They have worked out that they don’t think they can win by asking people to positively vote Conservative. Their only hope of winning is to play a relentlessly negative grievance-based campaign in the hope that they don’t win by the front door but by the back door."

Mr Blair deflected the attacks on his character at an education briefing where he told the audience that the Tories’ attacks on him were nothing as compared to the "all-out assault" they planned for public-sector schools.

He said: "The Conservatives can mount any number of attacks on me personally. They don’t matter. They’re just part and parcel of the Tory plan to sneak to power through the back door.

"What matters to me is stopping the attack they are planning on every school in the country."

Labour’s fears that a low turnout by Labour supporters on May 5 may hand victory to the Conservatives were underlined by a series of new polls today, which show their lead shrinking sharply.

Charles Kennedy, the Liberal Democrat leader, said that the Tories had "concluded they are losing this election", causing them to mount "the most negative form of personalised campaign".

Even Lord Tebbit, a former Tory party chairman, appeared to suggest today that the Conservatives had focused too heavily on negative campaigning, saying: "We are not sufficiently strong in ensuring a vision of a different country."

Mr Howard told supporters in Edinburgh this morning: "The message I think people should send to Mr Blair is ‘we have had enough of your broken promises, we have had enough of your talk, we have had enough of you’.

"Mr Blair doesn’t like being held accountable, but I think it’s very important he should be held accountable.

"I think that’s what general elections should be about. May 5 is your chance to tell Mr Blair where to get off."

Citing examples ranging from tax increases to the fate of Scotland’s infantry regiments, he added: "That’s 66 broken promises Mr Blair - and that’s why your character is an issue at this election."

Labour, which began its campaign by insisting that Conservative plans to make a £35 billion cut in public spending was equivalent to sacking every teacher and nurse, today continued to court the family vote with a second day focusing on education.

Mr Kennedy, buoyed by the latest Times/ITV tracker poll which showed the Lib Dems up by 2 percentage points, said that the Tories had given up hope of winning the election and were now "falling back on the most negative form of personalised campaign".

He added: "It won’t do them any good. "I think they are the losing team in this election while we are looking increasingly the team which is winning."

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