After a madcap return from a Caribbean holiday, a flurry of campaigning, secret top-level meetings with rivals Rishi Sunak and Penny Mordaunt and a major air campaign, Boris Johnson announced shortly before 9pm last night that he would not be running for Prime Minister after all of the Prime Minister.

It was the most Boris Johnson way to admit defeat: I am a winner who could beat the Conservatives in 2024, I have the numbers (he claimed 102 supporters), I could do it if I wanted to, but now is not the time.

His team said all weekend that he had the numbers and that he was preparing to run, despite only having 59 public endorsements at last count.

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Thus his exit was a bit of a shock to some of his fans. Conservative MP James Duddridge tweeted: “Well that was unexpected. Go to sleep!”

There was a lot of skepticism – and still is – about whether Mr Johnson actually reached the required 100 threshold.

But what was far more evident was that the momentum was firmly with his opponent Rishi Sunakwhich now has over 150 followers.

Support came from all wings of the party – including, crucially, standard-bearers on the right such as Lord Frost, Kemi Budenock and Suella Braverman.

What became clear over the weekend for Mr Johnson was that – although he had strong support – memories of the July chaos, his resignation and the upheaval that followed are still fresh in the minds of many MPs.

As one of his key supporters told me last night: “The coalition against Boris is very vocal and he thinks two-thirds of the party is against him and it will make the party ungovernable so he can’t do it and it will go the way of Liz Truss.”

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In a statement, Mr Johnson said as much – writing that he had “unfortunately come to the conclusion” that trying to return to No 10 now was not the right thing to do. “You cannot govern effectively unless you have a single party in Parliament.”

While Mr Sunak had hoped to beat Mr Johnson by a two-to-one margin among MPs, the former prime minister would likely win the vote if Conservative Party members had their say.

The embattled Tories would find themselves in the worst of all worlds with another prime minister the parliamentary party did not want.

There was a question mark over whether Mr Johnson would be able to fill all the posts (up to 170 MPs) in his government, given that many simply would not work under him.

At least one MP has said he will resign if Mr Johnson returns to No 10 under these conditions – amid talk of mass uprisings, defections and even the possibility of a Tory caucus bringing down the government in favor of a general elections. Mr. Johnson may have concluded that he had no choice.

But the seeds of divisiveness were visible in his statement last night. Mr. Johnson’s remarks that he “approached” Rishi Sunak and Penny Mordant “come together in the national interest” – but was overruled – likely to the cheers of his most ardent backbenchers.

It was Nadine Doris last night: “Barris would have won the members’ vote – already got the mandate from the people. Rishi and Penny, despite Boris’ pleas, refused to join forces, which would have made governing completely impossible. Penny effectively asked him to stand down for her. It will be now it is impossible to avoid a general election.’

And just as Mr Johnson faced a group of bitter enemies on the backbenches, so will Mr Sunak – in the form of Johnsonites who will never forgive the man they believe brought down the former prime minister.

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Mr Sunak looks set to become the next Prime Minister after losing out to Liz Truss in the summer.

He could be announced as the party’s new leader at around 2pm if he is the only MP to receive 100 nominations.

However, there will be a mad scramble for Ms Mordaunt’s votes as she tries to use Mr Johnson’s refusal to cross the line and onto the ballot.

She currently only has 25 public followers, so it’s a long shot, but some Johnson fans may reach out to her just to try to block Mr. Sunak.

One person familiar with Johnson’s camp suggested last night that many of his supporters may privately switch to Ms Mordaunt on the ballot to derail Mr Sunak’s coronation.

And as for Mr. Johnson, he may be reluctantly putting the matter aside for now, but there’s a hint in that statement – just like when he left with the words “hasta la vista baby!” – that he might come back: “I believe I have something to offer, but I’m afraid it’s just not the right time.”

Will he stay in parliament and serve it out if, if ever?