All three major party leaders were out on the road campaigning on Wednesday in the final days before the general election on Thursday.

Frontrunner David Cameron, leader of the main opposition Conservative party, was keen to demonstrate his energy as he embarked on a campaign that kept him awake through Tuesday night and into Wednesday morning.Cameron met nightworkers like bakers and fishermen.

Earlier he had made the highly unusual move of traveling to Northern Ireland. British party leaders hardly ever campaign in the province, because it has its own long-established political parties, which are based on sectarianism.

But the tacit support of the Ulster Unionist members of parliament (and in the last parliament there was only one) may well prove crucial for Cameron to take power after an election, which opinion polls are still saying will produce no party strong enough to form a majority government.

The Daily Telegraph, the most loyal of the Conservative national newspapers, reported on Tuesday that Northern Ireland's Democratic Unionist Party, which is defending nine seats at this election, was prepared to form a coalition with the Conservatives.

On campaign in Northern Ireland, Cameron courted the unionist parties, "This election presents a new opportunity to participate in the mainstream of British politics, in which people in Northern Ireland can participate at all levels of government in the UK -- from the council chamber right the way to the Cabinet table itself."

The prime minister and leader of the ruling Labour party Gordon Brown, took his doomed campaign to the north west of England and an election rally in the largely Labour city of Manchester.

The party faithful cheered as Brown delivered a message designed to pull Labour's traditional support back and to shore up wilting confidence in the final few hours of the campaign.

Earlier he had made a bid for Lib Dem voters when he told college students in the English Midlands, "There is an anti-Conservative majority in this country but most of the seats that are up here and in this area are a fight between the Labour party and the Conservatives. A vote for the Liberals may allow the Conservatives to be elected."

"Please make sure that you cast your vote in a way that we can secure the recovery, build our public services and make sure that we build also the jobs for the future in this country."

Some in Labour still believe they have the slim chance of holding onto enough seats to be able to form a coalition with the third party in British politics, the Liberal Democrats, in a bid to keep the Conservatives out of power.

Under this scenario Brown could lose the election in seats and number of votes cast and still remain prime minister.

Labour was hit by another defection from its stable of newspaper supporters. The Financial Times dumped its support of Labour and threw its weight behind the Conservatives, joining several other national newspapers who have all deserted the ailing ruling party in recent days.

There were signs of disagreements at the top of the Labour party in the face of looming defeat, with three Cabinet members either urging or coming close to urging Labour voters to vote tactically, to support the Lib Dems in places where they stood a better chance of defeating the Conservatives.

Former Labour prime minister Tony Blair entered the controversy, firmly opposing calls for tactical voting. In an interview with The Guardian newspaper, Blair, who was absent from much of the campaign, said he thought the vote would be a verdict on his time as prime minister as well as on Brown's.

He added "It is simple -- vote for what you believe in. If you think their (the Lib Dems) policies are good, vote for them, but if you don't, don't. The Lib Dems are not going out to people and saying 'vote Labour' -– they are trying to take seats off us."

The leader of the Liberal Democrats, Nick Clegg, shifted ground somewhat on Tuesday to assert that proportional representation, reform of the current first-past-the-post voting system which does not favor his party, was not an absolute demand for a coalition.

"I have never talked about preconditions for talks. I have always talked about the things I want to fight for, the changes I want to fight for," Clegg said in a TV interview.

"Yes, I want a new political system because I think the old one is bust."

Clegg needed to leave room for him to deal with the Conservatives if the general election results in a hung parliament with no party holding a majority of seats in the next House of Commons.

An opinion poll released on Tuesday evening and carried out by Comres for ITV News and The Independent newspaper put the Conservatives on 37 per cent, Labour on 29 per cent and the Liberal Democrats on 26 per cent, all the figures being unchanged on a poll in the same series 24 hours earlier.

A YouGov/Sun poll also released on Tuesday evening put the Conservatives on 35 per cent, Labour up to 30 per cent and the Liberal Democrats dropping to 24 per cent.

The huge boost given to the Lib Dems in the wake of Clegg's victory in the first TV debate has drifted away somewhat, as some voters appear to have returned to the parties they first supported. However there are many voters who are still undecided or who may change their minds, making an already difficult-to-call election even more complex.

But on those figures the Conservatives would be tantalisingly close to a majority government in one poll, if they could swing the support of the unionist parties from Northern Ireland, and in the other they would have more votes but fewer seats than Labour.