Theresa May is set to admit she’s run out of road and step down as Prime Minister.
But what happens then?
Once she officially hands in her notice, a sequence of events will be set in train to confirm her replacement.
Whoever comes next will have to decide what happens with Brexit and whether to call a General Election.
Here’s what happens when Theresa May quits – and answers to more questions about the aftermath.
When will Theresa May stop being PM?
Even after Theresa May stands down as Tory leader she will remain PM, unless she nominates a caretaker to hold office until the leadership contest is over.
David Cameron remained in office while the race to replace him, which Mrs May won, went ahead in 2016.
But to stand down as Prime Minister, Mrs May will have to go to the Queen and formally resign and invite the monarch to nominate her successor.
How will the Conservatives pick the next leader?
Candidates must be nominated by two sitting Conservative MPs.
If several names are put forward to lead the party, then a vote is held among Conservative MPs to whittle the field down to two.
Votes are held among MPs, at intervals decided by the Chairman of the 1922 Committee, and each time the candidate with the least support is eliminated.
Once there are two candidates, they are both put to the Tory membership – around 120,000 or so people – to choose the new leader.
How does this effect Brexit?
We are still set to leave the EU on October 31 – but Theresa May has hoped to pass her Withdrawal Bill and leave earlier.
Her successor will inherit the same deeply divided Parliament, where MPs are implacably opposed to a No Deal Brexit , with no majority without the support of the Northern Irish DUP.
So while they will no doubt have their own vision for how to take Britain out of the EU, the paralysis that grips Parliament won’t disappear just because Theresa May does.
Who are the frontrunners to replace Theresa May?
Boris Johnson is the favourite with William Hill offering odds of 7/4 of him being the next Tory leader.
But it a crowded field and former Brexit Secretary Dominic Raab, 4/1, and Jeremy Hunt, 8/1, are also seen as challengers, with Mr Hunt reportedly Mrs May’s favourite to replace her.
Will we have a general election?
Labour leader Jeremy Corbyn has long called for a general election, but it is not clear if Mrs May going will make this more likely.
But whoever replaces her as PM will still face a divided and hostile Parliament and may want earn their own majority.
Full odds for the next Prime Minister
- Boris Johnson 7/4
- Dominic Raab: 4/1
- Jeremy Hunt: 8/1
- Michael Gove: 14/1
- Sajid Javid: 16/1
- Penny Mordaunt: 20/1
- Rory Stewart: 20/1
- Matt Hancock: 22/1
- Andrea Leadsom: 22/1
- Amber Rudd: 50/1
- Liz Truss: 25/1