Gordon Brown, David Cameron and Nick Clegg are into their final day push for votes ahead of the UK election, visiting towns across Britain.
Conservative leader Mr Cameron, who campaigned through the night, said he was fighting "for every vote".
Labour Prime Minister Mr Brown said he was "determined" and "resolute" and was "fighting for Britain's future".
But Lib Dem leader Nick Clegg urged people to use their votes to prevent a return to the two-party "stitch-up".
In other election developments on Wednesday:
In Scotland, the SNP, Lib Dems, Labour and Tories
In Wales Plaid Cymru leader Ieuan Wyn Jones, Welsh Lib Dem leader Kirsty Williams, Welsh Secretary Peter Hain and Tory leader David Cameron are
Other parties seeking votes and hoping to make a breakthrough on the last day of campaigning are the
Mr Cameron campaigned overnight, talking to shift workers in Cumbria, Lancashire, Yorkshire and Lincolnshire.
He told GMTV it was the "most important election in a generation" and he had campaigned through the night because he "didn't want to waste any hours on the last day and a bit".
He said: "I don't want to take anything for granted, it's a very important election, it's a close election and I'm fighting for every vote right down to the wire."
Asked about the Tories' narrow poll lead, Mr Cameron said: "I never believed this election was going to be easy. Elections are meant to be a challenge. The British people don't hand you the government of the country on a plate, quite rightly they are making us work for it."
After a day in which cabinet ministers Ed Balls and Peter Hain urged tactical voting to keep the Tories out - Mr Brown, the prime minister, told a phone-in on BBC Radio 5 live that he wanted all Labour supporters to vote Labour.
Some polls have suggested that Labour could come third in terms of overall votes - yet still get enough seats to form a government.
Mr Brown acknowledged that in some areas the Lib Dems and Tories were battling it out for first place, but said: "People will judge us also on the number of votes we have got, as well as the number of seats."
After dealing with a range of listeners' questions on topics including immigration, welfare and mental health funding he said: "I'm a fighter, I don't give up. I'm fighting for Britain's future in my view, I'm fighting because I believe in what I'm doing."
In a speech in Bradford, he said he was "determined" and "resolute" and told supporters: "This is not a Conservative moment."
Meanwhile Nick Clegg, who is hoping his party can make the breakthrough from their traditional third place, addressed a rally in Eastbourne, before heading north to Durham then Sheffield.
He has been visiting seats he would have considered unwinnable a month ago - in Durham two seats were won with large Labour majorities in 2005 - and he is urging disaffected Labour supporters to come over to him.
Mr Clegg said in a speech: "It's now time to make a choice, a choice between the politics of the past, the old politics and something new and different for the future."
"If David Cameron or Gordon Brown get into Number 10, nothing, nothing will really change at all... We cannot let that happen."
He added: "We will deliver the real change, the real fairness that people want."
As polls continue to suggest the election will result in a hung parliament, Green leader Caroline Lucas - who hopes to become her party's first MP - told the BBC there were "pretty exciting days ahead" as the Greens would get "that bit more influence".
"It's incredibly important that you've got people that will be there day-in, day-out, saying the environment is a crucial issue, doing good action on it, but also showing that it benefits people," she said.
Plaid Cymru's leader Ieuan Wyn Jones, campaigning in Llanelli, said whoever won power, Wales was facing cuts: "By voting Plaid we can defend Wales better against those cuts and the greater the vote for Plaid, the better the deal we can get for the people of Wales."
And SNP leader Alex Salmond said only his party could protect Scotland from the "worst impact of a Tory or Tory-led government": "Labour are finished, while the Tories are arrogantly saying they can rule with no Scots MPs and the Lib Dems are ready to do a deal with David Cameron."