Boris Johnson has this evening pulled out of the Conservative leadership contest, leaving the field clear for Rishi Sunak. Only this morning his MP supporters had been insisting that the former prime minster had secured the 100 MP nominations required and would definitely run, but Johnson says the opposition to him is such that he will not enter the race – but there were severe doubts about this, with some MPs saying they were being approached by a desperate Boris team that did not have the numbers but had claimed otherwise. Sunak had more than twice as many declared nominations.

In a statement released this evening, Johnson he’d hit ‘the very high hurdle of 102 nominations’ and so there was a good chance he could be ‘back in Downing Street on Friday’ given his popularity with the membership. But upon reflection, he said, he’d better not. From his statement:-

 ‘I believe I am well placed to deliver a Conservative election victory in 2024. In the last days I have sadly 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. 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. Therefore I am afraid the best thing is that I do not allow my nomination to go forward and commit my support to whoever succeeds.’

So, what was the trigger? There were growing nerves among Johnson backers this afternoon that he was yet to formally say he would enter the race. What’s more, the number of MPs publicly backing him – at 60 – was suspiciously below the 100 required and dwarfed by the 152 who had declared for Sunak.  Repeated claims from his supporters that he had hit the threshold of 100 MPs were met with some scepticism given it would have meant that two in five of his supposed supporters were not willing to go public.  Even now, when he says he won 102, it’s unclear why almost half wanted to keep it secret.

It also became clear that the Sunak campaign had the momentum – with the former chancellor winning the backing of several leading Tories on the right including foreigner Boris loyalist Suella Braverman, Kemi Badenoch and Brexit spartan Steve Baker. While Johnson’s supporters argued he only needed to hit 100 backers as the membership would pick him over Sunak, it pointed to problems governing were Johnson to go all the way. This evening George Osborne warned on the Andrew Neil Show that Johnson could quite quickly find himself unable to get any business through parliament given the level of MP opposition.

Johnson’s decision to step down means the chance of a Sunak coronation tomorrow has gone up. The only other candidate left in the race is Penny Mordaunt who has been struggling to pick up nominations. Johnson’s supporters are now to play for. Several of these MPs are already unhappy at being marched up a hill by Johnson only for him to pull out.

But nothing in this race is final. Mordaunt could now gain some from Johnson backers. Her campaign team have said this evening that she fights on and ‘is the unifying candidate who is most likely to keep the wings of the Conservative Party together’. If she hits 100 nominations by 2pm tomorrow and demands a members’ vote, she’ll get one. But the betting markets put her chances at 5 per cent, so she might decide to bow out now (even Nadhim Zahawi is now backing Sunak) and it could all be over tomorrow.

Is this the end for Johnson? That seems unlikely. In his message this evening, Johnson concluded by saying ‘I am afraid that this is simply not the right time’. That’s the message senior Tories have been telling him as they have attempted to talk him down – that by bowing out now, he could make a comeback in the future.

Listen to Katy Balls, James Forsyth and Kate Andrews discuss Boris’s surprise withdrawal from the leadership race: