It turns out that Harold Wilson was wrong when he said a week is a long time in politics.
In these fraught times at Westminster a long time is measured in hours, minutes or even seconds.
On Tuesday night ministers were suggesting in private that Theresa May would lose today's vote of confidence in her leadership.
A key rule of the process - that victory would keep her in place for a year - was counting against her on Tuesday.
Why? Because that would mean she would lead the Tories into an early general election, the one thing Tory MPs agree must not happen.
Wind the clock forward to Wednesday morning and another rule of the process - that the confidence vote must be held promptly - is now counting in the prime minister's favour.
No 10 aides are taking nothing for granted and know full well that the end of the May premiership could well be signalled at 21:00 GMT on Wednesday when Sir Graham Brady, the chairman of the 1922 committee, reads out the result.
But if Theresa May pulls it off, there are three factors that would explain how she could replace Bill Clinton as the "comeback kid".
The factors are:
- Speed. The speed of the contest has allowed the prime minister to frame the choice before MPs. Sir Graham Brady gave a flavour of the speed of the contest this morning when he said he spoke to May at 21:30 GMT on Tuesday night and made a point of announcing before the financial markets opened on Wednesday morning that a vote would be held. Amid murmurings from his fellow Brexiteers that he was skewing the vote in her favour, Brady said he was following the rules which say the vote should be held promptly.
- Framing. In framing the choice before Tory MPs this morning, the prime minister reached out to the majority of Conservative MPs who want a negotiated Brexit. She said her successor would not be in place by 21 January - the legal deadline for a deal. That could mean that the next leader may have to extend article 50, delaying or even stopping Brexit.
- No alternative candidate. A change in party rules means that the prime minister may be helped by one big difference between today's vote and the last time a sitting Conservative prime minister was challenged without having triggered a contest. In challenging Margaret Thatcher, Michael Heseltine could stand up and outline how he would deal with the two big issues that had prompted the loss of confidence in Thatcher - the council tax and Europe. Wednesday is a confidence vote, not round one of a leadership contest. That means that none of the likely contenders in a leadership contest that would be triggered by a loss tonight - Boris Johnson, Dominic Raab, Amber Rudd and Sajid Javid - are on the airwaves. So the only big voice is Theresa May.
During prime minster's questions, there were big cheers on Mrs May's benches when Kenneth Clarke warned that a leadership contest would be a terrible distraction.
The man she describes as her "rock" - her husband Philip May - watched Theresa May from the Commons gallery.
"The prime minister is in remarkable form," one aide said. No 10 will be hoping that mood lasts beyond 21:00 GMT Wednesday.