Rishi Sunak could be declared the next prime minister within hours after Boris Johnson ruled himself out of the race for No 10, with uncertainty over rival Penny Mordaunt’s prospects of securing sufficient support from MPs.
Tory MPs will choose who they want to be their new leader in the first stage of the contest on Monday, should both remaining candidates get the 100 nominations required to reserve a place on the ballot.
If Ms Mordaunt falls short of this total by the deadline of 2pm, or pulls out of the contest, Mr Sunak will take charge of the party without the need for a vote.
It comes after Mr Johnson dramatically withdrew from the race – having never officially entered, claiming he had the numbers but admitting he could not unite his warring party.
In a statement on Sunday evening, he said there was a “very good chance” he could have been back in No 10 by the end of the week if he had stood.
However his efforts to “reach out” to his rivals – Mr Sunak and Ms Mordaunt – to work together in the national interest had not been successful, he said, so he was dropping out.
While Mr Sunak, the former chancellor, already has more than 140 public declarations of support, Ms Mordaunt, the Leader of the House, had fewer than 30 on Sunday night.
Her team are hoping that the departure of Mr Johnson will see a swathe of MPs who were backing him or are yet to declare swing behind her.
A campaign source confirmed she was still in the running on Sunday, arguing she was the candidate who Labour feared the most.
“Penny is the unifying candidate who is most likely to keep the wings of the Conservative Party together and polling shows that she is the most likely candidate to hold on to the seats the Conservative Party gained in 2019,” the source said.
“Rishi is immensely talented, will command a strong majority in the parliamentary Conservative Party, and will have my full support and loyalty,” he tweeted.
Ms Mordaunt has limited time to get the necessary nominations. If she fails, Mr Sunak will be declared leader without a contest.
If she does get the numbers, MPs will then decide which of the two candidates they prefer in an “indicative” vote.
There will then be a final online poll of party members to decide the outcome, with the result due on Friday – unless one of the candidates pulls out.
There are some in the party who would like to see an uncontested “coronation” to avoid a repeat of what happened with Liz Truss when members voted for a leader who did not have the backing of MPs.
Ms Mordaunt could find herself under pressure to withdraw if she finishes a long way behind Mr Sunak in the poll of MPs – should it go to a vote, even though she is popular with the Tory grassroots.
At the same time, however, many activists – many of whom loathe Mr Sunak for his role in bringing down Mr Johnson – will be furious if they are denied a say in the contest.
In a statement on Sunday evening, Mr Johnson said he had been “overwhelmed” by the support he had received from people urging him to run just weeks after being forced out by his own MPs after one scandal too many.
If he had stood, he said there was a “very good chance” the members would have voted him back into No 10 by the end of week and that he would have been “well-placed” to lead the party to victory in a general election in 2024.
However, he said he had come to the conclusion that “this would simply not be the right thing to do”.
“You can’t govern effectively unless you have a united party in Parliament,” he said.
“And though I have reached out to both Rishi and Penny – because I hoped that we could come together in the national interest – we have sadly not been able to work out a way of doing this.
“I believe I have much to offer but I am afraid that this is simply not the right time.”
Some MPs were sceptical of his claim to have secured the 100 nominations needed to go forward, with the number of public declarations of support falling far short of that.
Some at Westminster suspected that he chose to withdraw rather than face the humiliation of having to admit he could not get the numbers.
Sunak-supporting Tory MP Tobias Ellwood, meanwhile, dismissed calls from Labour for a general election.
“The country does not want further economic instability,” the chairman of the Commons Defence Select Committee told the BBC.
“And what you’d get if there was a general election is it would not be clear as to which direction the country would go, there’d be greater upheaval, the markets would then be spooked again.
“There would probably be a run on the pound, that would see interest rates climb (and) mortgages go up as well. This isn’t the leadership the country wants.”