BBC deputy political editor James Landale, and the BBC correspondents travelling with the party leaders, give their verdict on the 2010 election campaign:
THE CAMPAIGN REVIEWED: BY JAMES LANDALE
There is a purity to the end of an election campaign. Gone is the grandiloquence, the rhetoric of the early stages, the vision of the manifestos.
Instead we see the parties as they really are, their messages shorn to the bone, the exhausted desperation in their eyes as they struggle on for the last vote that in an election as tight as this could make the difference.
Thus Labour's appeal to the electorate: do not risk all on the Tories - they would threaten the recovery and cut child benefits for the middle classes. Thus the Conservatives: only we can see off Gordon Brown and ensure the change you are desperate for. And thus the Liberal Democrats: do not waste this moment, this opportunity of a generation to transform anger over expenses into lasting political reform.
But all three party leaders know just what we know, namely that no one can really predict how this election will play out. It is one thing to lose knowing the game is up; it is another to lose when success has been within reach.
So this is what the election has come down to. The early skirmishes about national insurance seem from a distant age. Who can recall the detail of the manifestos, the Tories' "big society" and "great ignored" members of society, Labour's "future fair for all", the Lib Dems' "change that works for you"?
We shall soon forget the heckling, the media scrums, the spoofed posters and election broadcasts, the walk on role of a tanned former prime minister. The promise of an internet election failed to emerge, the twitters and the blogs talking above all to each other, not the electorate.
But two things will linger in the memory. The television debates changed the balance of power in this election, introducing Nick Clegg to an electorate seemingly hungry for change, keen for an alternative to what we can perhaps for a few more hours safely call the two largest parties.
The Lib Dem leader revealed himself to be articulate and passionate, comfortable in his skin and in a format that his two opponents struggled at first to master. Whether this signals the political earthquake that some hope for depends still on how people vote on Thursday; some polls are suggesting the Clegg starburst is on the wane.
And of course the name of Gillian Duffy will live on, a moment in the election that revealed the prime minister raw and unplugged. Or plugged, as it turned out. The polls suggest Mr Brown's decision to call this Rochdale pensioner a bigot may not have changed public opinion that much, merely confirming existing views rather than changing minds. But some Labour candidates on the ground disagree, saying it will depress the party's vote.
I wrote earlier that there is little time for grandiloquence at this stage of a campaign. There is one exception. In recent days, the prime minister appears to have found a late breath, a voice he perhaps had lost in office and has rediscovered now the finishing line is near. In his speech to an audience of religious community organisers on Monday, he relaxed into himself and let rip with the oratory of an old school preacher. Not to everyone's taste perhaps, and its electoral impact uncertain, but authentic Brown nonetheless.
As for David Cameron, he has put few feet wrong in this campaign, maintaining a discipline and energy throughout, learning the new discipline of the television debate, improving his performance each time.
His aim, above all, to reassure voters that he has the right stuff to lead the nation. But his vision of a "big society" that would transform public services in this country, what his manifesto called an "invitation to join the government of Britain", was perhaps sprung on the electorate too late with many voters still struggling to understand what it might mean for them.
So enough is enough. Decision time is almost upon us. This is, let us not forget, a general election of 649 separate contests - the voters of Thirsk & Malton must wait until May 27 because one of their candidates died. There will be unexpected results, swings will be local as much as national. The Greens are fighting to win their first seat in parliament. UKIP are challenging the Speaker in his Buckingham constituency. The voters of Barking are being courted by the British National Party. Plaid Cymru and the Scottish Nationalists are arguing that their MPs could make the difference in a hung parliament.
And yet, after all this, after all the millions of words, the hours of television, the leaflets, the canvassing, the speeches and the relentless travelling, thousands of voters are still telling the pollsters they still have yet to decide which argument they find most convincing, as many perhaps as 40 per cent of voters across the country. Their decision in the coming hours will make a difference. But few know how.
BY IAIN WATSON WITH GORDON BROWN
Insomnia is the clear winner in this campaign. Late last night Gordon Brown demonstrated that he was steeled for the struggle ahead by visiting shift workers at a Sheffield forge - although achieving a poll lead seems as difficult as turning base metal into gold.
Gordon Brown is hoping undecided voters will vote Labour on the day
On Wednesday morning the prime minister was up with the lark in Leeds to visit a 'fresh produce' market. But he knows he has to convince voters his New Labour product isn't stale. The party has all but abandoned the line that they - just like the opposition - also represent change in what Gordon Brown calls 'a post crisis election'.
Instead, he is now warning against 'the wrong kind of change' with the Conservatives. In other words he has retreated to his core message that his opponents would wreck the recovery and cut public spending more savagely and speedily than Labour.
The prime minister is certainly demonstrating he has the energy to carry on with a round of regional and national TV radio appearances today and a tour of marginal seats in northern England and Scotland.
But the polls suggest he still has trouble getting the political message across. Labour's strategists are consoled by the perception that the party is pulling ahead of the Lib Dems as polling day approaches and that the prime minister has injected some passion into the closing stages of the campaign.
Their hope is that those undecided voters who still have doubts about David Cameron will now turn to Gordon Brown in the privacy of the polling booth and not to Nick Clegg. While their expectation is that they can deny the Conservatives outright victory, few in truth believe they stand on the brink of an historic fourth Labour term.
BY CAROLE WALKER WITH DAVID CAMERON
David Cameron bought us all fish and chips to fortify us through the long night, ordering "salt and vinegar all round please".
At The Border Cod in Longtown, Cumbria, Mr Cameron told fellow customers he didn't expect to get much of an idea about the result of the election until three or four o'clock on Friday morning.
There was little sign of the tension which he must surely be feeling as voters prepare to cast the votes which will determine his future.
The Tory leader had a cup of tea with fire-fighters in Carlisle, dropped in on the nightshift at an engineering company in Darwen, Lancashire and chatted to supermarket delivery staff in Wakefield.
David Cameron has remained upbeat throughout the campaign
Mr Cameron rejected suggestions this final burst of round-the-clock campaigning was a stunt. He said he wanted to show how hard he was prepared to work to win the trust of the British people.
It was also a practical rebuttal of his rivals' claims that he's complacent
"thinks he can waltz into Downing Street" as Lord Mandelson put it.
By dawn he'd reached Grimsby, to see fishermen sorting their catch. Holding up a giant halibut may have dubious electoral benefits, but the sun rising over the docks provided a momentary sense of tranquillity in the midst of the frenetic tour.
Overnight he acquired the backing of the Daily Mail and the TV mogul Simon Cowell. But the latest polls suggest the Conservatives are still short of the support they need for an outright victory.
The Conservative leader has remained relentlessly upbeat throughout this campaign. But he is genuinely angry at what he says are Labour "lies" about Tory cuts, and accuses Gordon Brown of a negative campaign designed to frighten the voters.
The Conservative campaign has been more positive, focusing on the promises to cut National Insurance contributions and corporation tax, to reduce the role of the state. But outside the leader's circle campaigners have found it difficult to inspire voters with his vision of the big society. Privately some acknowledge how hard it is to compete with Labour's dire warnings of economic mayhem if the Tories win power.
Though the prospect of a hung parliament has loomed over the entire election, Mr Cameron has resolutely refused to talk about a possible deal with the Liberal Democrats... or with the Democratic Unionists. He insists he's still working flat out for a clear victory which would enable him to roll up his sleeves and start to deliver the change he has promised.
Mr Cameron always knew he faced an electoral mountain, needing to gain 116 seats for a clear majority. He has focused throughout on winning support in the marginal seats that will decide the outcome.
On the eve of polling day, the result still hangs in the balance with millions of people still to decide where they'll place their cross.
Throughout the day the Cameron campaign has rolled on, delivering leaflets in Nottinghamshire, talking to paramedics in Dudley, visiting a school in Wales. There will be no let-up until the final rally in Bristol tonight - 36 hours since he set out from London at the start of this marathon tour.
He'll find out soon enough whether he's done enough to persuade voters to trust him to lead the country.
BY MIKE SERGEANT WITH NICK CLEGG
So Nick Clegg's fascinating election journey nears its end. His personal profile has been transformed during this campaign.
A couple of weeks before the election was called, I was the only national journalist at one of his speeches. Now there are dozens of reporters and photographers trying to elbow each other out of the way during the final flurry of events.
Nick Clegg has always said that anything is possible
The Lib Dems are hoping to keep up the energy levels and excitement as their man tries to race across the finish line.
The mood on the battle-bus and the leader's plane has been getting a little more nervy, though. Party strategists always knew that Liberal Democrat support could be squeezed as decision-time approached. They were hoping it wouldn't happen.
Is Nick Clegg wishing this election had been held a week ago? Then his party was regularly hitting 30% in the polls. Now, there are some signs that support may have peaked a little early.
But, at the end of such a close, fluid campaign, nobody wants to stick their neck out now and make rash predictions. Mr Clegg has always said that "anything is possible". We are about to find out.
Wednesday's final visits see the Lib Dem leader trying to make incursions into what might have been considered safe Tory and Labour areas a month ago (Eastbourne and Durham respectively). Of course winning seats is vital for the party. But aides say that share of the national vote will be really important as well.
The more people vote Lib Dem, the stronger Mr Clegg's hand will be after the election. That's why he'll be doing all he can to urge those who've warmed to him during this exciting campaign not to get cold feet tomorrow.