Tony Blair appealed to voters not to let the Tories back in to Downing Street by the back door, as opposition parties kept up the pressure over Iraq.
Mr Blair urged voters not to stay at home
Shadow Foreign Secretary Michael Ancram wrote to Mr Blair asking for more information on the naming of Iraq weapons expert Dr David Kelly.
The Lib Dems announced that ex-BBC boss Greg Dyke, who quit Labour over Iraq, was to join the party's campaigning.
The prime minister stressed the fight was between Labour and the Tories.
During an election campaign rally for Labour supporters in Long Eaton, Derbyshire, he appealed to voters not to "hand the keys of Downing Street" to Michael Howard's Conservatives.
Acknowledging dissatisfaction from core supporters, he said of course there were "disappointments and disillusionment".
"But when you look back I pose one simple question: faced with a choice over what we have delivered and a Conservative party that would go back to 1997 and carry on where they left off, tell me, is this country not better, fairer, stronger?"
This followed earlier appeals to disaffected Labour voters who might be considering a vote for the Lib Dems.
He said: "It is Labour versus Tory. Anything else is a Tory vote by the back door and they (the voters) should have nothing to do with it."
Labour claim the Tories could win if just one in 10 of those who voted Labour in 2001 don't back them this time.
But Charles Kennedy dismissed the claim saying: "There is no chance whatsoever of the Conservatives getting in by the back, the side or any other door because they have lost this election and people know they have lost this election."
During a visit to Leeds, the Lib Dem leader said that Labour was really worried about the "millions of people" who wanted to elect Lib Dem MPs.
The Lib Dems also announced former BBC Director General Greg Dyke was soon to join Mr Kennedy on the campaign trail.
Former Labour supporter Mr Dyke, who was sacked in the wake of the Hutton Inquiry into the death of Dr Kelly, has switched his allegiance to the Lib Dems because of Iraq.
And Mr Ancram kept up the pressure over the issue repeating calls for clarifications over the naming of Dr Kelly.
'Bit by bit'
Mr Ancram accused the prime minister of ducking his questions.
He complained he had received no response to a letter demanding an explanation of what he saw as the prime minister's admission during a TV interview that he had a role in the leaking of Dr Kelly's name to the press.
Downing Street decided to publish the full legal advice on war in Iraq
Mr Blair told BBC Newsnight's Jeremy Paxman, "we" thought it was the right thing to do - although he had previously denied having a role in the decision to name the Iraq expert.
Mr Ancram called for an explanation and said in his letter to Mr Blair: "I would have thought that you would have learned by now how, bit by bit, the truth always comes out."
Former Labour leader Neil Kinnock who suggested speculation of the war's legality could have been "laid to rest" by the publication of the attorney general's legal advice, said the focus on the Iraq war over the few days had been a "massive diversion" of Labour's campaign.