What's at stake for the parties as Oldham result looms?
None of them is here.
But all three have an anxious wait.
As the tellers empty the ballot boxes, and the count gets under way, the leaders of the main Westminster parties have three or four hours to endure, while the first voters' verdict of 2011 is still unknown.
That wait will be more nervous than on many other occasions because in this by election, even as the polls close, the result seems so hard to know.
National surveys have put Labour comfortably ahead. But the curious circumstances of the Oldham East and Saddleworth by election make it so hard to read.
The vote was triggered by a court ruling, the first of its kind for decades, when the Liberal Democrat candidate who was narrowly beaten in May overturned the result that had sent the former Labour MP Phil Woolas back to Westminster.
I've heard resentment towards the Lib Dem candidate for forcing the issue to court, so leaving the area without an MP for months.
The constituency is a patchwork of communities that have little in common; from the narrow terraces of Glodwick, a largely Asian area on the edge of Oldham itself, to the comfortable village of Uppermill, in Yorkshire, with its teashops and boutiques.
And of course this is the first by-election under the new government.
Not just the first under the government of a different party, but the first under the government of two parties, the first coalition in many years. And voters have told me of their frustration that this has been a national, not a local campaign.
So neither David Cameron, nor Nick Clegg, nor Ed Miliband can be certain of the outcome. But all three know that the result could be critical to their political fortunes.
For Ed Miliband a good win could give a much needed kick-start to his leadership of the Labour Party.
A narrow win would furrow the brows of those who worry about his ability to pull in the votes. A loss, when Labour lead many of the national polls and are the incumbents, would give the doubters real cause to stop and wonder if they chose the wrong Miliband brother.
Test for Clegg
Nick Clegg might never have imagined his party would be tested at a by-election as part of a government. But a bad result and the consquences of his decision will feel all too real.
A big slump would give ammunition to those in his party who argue that going into coalition threatens the Lib Dems' identity and perhaps the party's survival.
Come a respectable second, and Lib Dem nerves won't lose too much sleep. Come a bad third, and Lib Dem grumbles could be hard to contain.
The most damaging prospect for Mr Clegg, curiously, could be a win for Mr Cameron, as it would support the argument that he glides on making unpopular decisions, while the Lib Dems take all the heat.
Not many serious bets in Westminster would be put on his Conservative candidate Kashif Ali, but local wise heads caution against writing him off. Phil Woolas had strong links and strong support in the Asian communities of the constituency.
And Kashif Ali has been quietly and effectively working there, and in other areas too. So could Mr Cameron be celebrating an unexpected victory? Well perhaps not.
The damage a Conservative victory would do to Nick Clegg, would be far more serious for David Cameron, than the flak the party leadership has taken internally for not putting their shoulder fully to the campaign.
Now the polling stations are closed, the three men now don't have much longer to wait.
But with all that is at stake and the uncertain outcome, it could feel like a very long night.