Helen Catt
Political correspondent

This may be an internal contest but, as with any other election, the 1922 Executive doesn't just take a candidate's word for it that they have 100 backers.

The process isn’t public, or published, but here’s my best understanding of how it works from speaking to people who are involved in various ways.

Two Conservative MPs have to act as a proposer and a seconder. They have to allow their names to be made public.

Then, 98 other Conservative MPs have to nominate them too but they can choose to remain secret.

Candidates have been collecting the nominations from MPs, either physically or by email, and will submit a form to the 1922 Executive.

I'm told the nominations are checked to make sure they are clearly backing them.

That's quite a lot of admin so candidates will have already booked a slot to go through theirs.

There isn't a lot of time for all this: nominations close at 14:00 BST on Monday; if there's more than one candidate then voting starts at 15:30 BST.

With Boris Johnson out of the leadership race, several Tory MPs have begun switching their nominations for the next party leader.

Here are the MPs who first backed Boris Johnson but are now supporting Rishi Sunak:

Nadhim Zahawi, MP for Stratford-on-Avon, said: "Rishi is immensely talented, will command a strong majority in the parliamentary Conservative Party, and will have my full support and loyalty."

Shailesh Vara, MP for North West Cambridgeshire, said: "Rishi led us as chancellor through the pandemic and I believe he is now the right person to lead us in these difficult times."

David Morris, MP for Morecambe and Lunesdale, said: "Now Boris Johnson has pulled out of the contest, I will be joining Rishi Sunak' team. Rishi is experienced, competent and will make a great PM."

And these former Boris-backers have switched to supporting Penny Mordaunt:

Michael Fabricant, MP for Lichfield, said: "I am deeply disappointed that Boris has chosen not to stand. I shall now nominate [Penny Mordaunt] to let the members of our great party decide who should be our leader and next prime minister."

Image source, Reuters

Chancellor Jeremy Hunt has endorsed Rishi Sunak to be Britain's next prime minister, in a piece in the Telegraph, external, comparing him to Winston Churchill in his willingness to speak the truth.

Hunt says: "Our public finances, market credibility and international reputation have taken a serious blow.

"To restore stability and confidence, we need a leader who can be trusted to make difficult choices. We have a leader who can do just that in Rishi Sunak."

Hunt says Sunak will "turn the page on what went wrong, take decisions in the national interest and rebuild the extraordinary potential of our economy."

Chris Mason
Political editor

Image source, Getty Images

With the former prime minister Boris Johnson out, the firm favourite to be the new prime minister is Rishi Sunak - and, unless Penny Mordaunt assembles an army of supporters many times greater than those currently signed up, and between now and lunchtime, Sunak's victory could be confirmed this afternoon.

Whatever happens there'll be a new prime minister by the end of the week.

Yes, a third prime minister in seven weeks.

An unprecedented level of turbulence; a calamitous series of events that most Conservatives acknowledge privately has amounted to a circus of absurdity deeply damaging to their party's reputation.

The winner will inherit the same groaning basket of problems that proved too heavy for Liz Truss to bear: a deeply divided party; spiralling prices, grim public finances and a chorus of opposition parties saying they have no electoral legitimacy.

But they'll hope too the Conservative Party's apparent insatiable appetite for insurrection may finally be sated. If it isn't, a toweringly difficult task will rapidly become impossible.

Image source, Getty Images

We're waiting to see where the nominations that were intended for Boris Johnson will go now.

Since Liz Truss resigned, we've been monitoring the number of public backings for those in the running to become Britain's next prime minister.

The threshold to be on the ballot is the backing of 100 MPs, and there are a total of 357 Conservative MPs in Parliament.

The candidates cannot nominate themselves, so taking away the two potential leaders leaves 355.

According to our tally:

• 155 MPs are backing Sunak
• 25 are backing Mordaunt

There are 54 who backed Johnson but haven't yet publicly switched support. Watch this space.

More headlines now from tomorrow's national newspapers, the majority of which lead with Rishi Sunak's position.

The Daily Express says that he's set to be crowned the next prime minister after Boris Johnson pulled out of the race for No10.

The Sun writes that he's on course to be Britain's new prime minister by tea time on Monday after Johnson stepped aside to avoid chaos.

The Daily Mirror reports that Sunak is on the brink of becoming Britain's latest "unelected PM". The paper says "humiliated" Johnson claimed he had the numbers for a return but feared he would split the party.

Image source, Daily Express

Image source, The Sun

Image source, Daily Mirror

Image source, Getty Images

On the subject of a general election, Labour's deputy leader Angela Rayner has repeated her party's call for one.

"Perhaps it's not surprising he's avoiding scrutiny: after all, he was so bad that just a few weeks ago he was trounced by Liz Truss," Rayner says.

"We need an election now - people deserve a vote on the future of the country," she says.

Image source, EPA

Former culture secretary Nadine Dorries says it will now be impossible to avoid a general election, taking aim at the remaining two leadership candidates, Rishi Sunak and Penny Mordant.

Dorries, a long time ally of Boris Johnson, tweeted , externalthat Sunak and Mordaunt, "despite requests from Boris, refused to unite, which would have made governing utterly impossible".

She said that Johnson would have won a members' vote, had he decided to run for the Conservative party's leadership.

Dorries, who stood down as culture secretary when Liz Truss succeeded Johnson as prime minister, said Johnson already had a mandate from the people.

She said: "Penny actually asked him to step aside for her" adding that "it will now be impossible to avoid a [general election]".

Essex MP Sir James Duddridge, who gave the first indication that Boris Johnson was intending to run in the Tory leadership race, has responded to the news the former PM has ruled himself out.

He tweeted, simply: "Well that was unexpected. Off to bed!".

Duddridge started the Johnson ball rolling when he said he'd been in touch with the ex-PM while he was away last week on a Caribbean holiday.

He told the PA news agency he'd received this WhatsApp message from Johnson: "I'm flying back, Dudders, we are going to do this. I'm up for it."

Monday's newspapers are dominated by Boris Johnson's decision not to run for PM.

The Times says Rishi Sunak is paving the way to become Britain's next prime minister and he could be named as Liz Truss's successor as soon as Monday.

The paper says it represents a "significant climbdown" by Johnson after he "told his supporters he was planning to stand" and claimed he had the support of 102 Tory MPs.

The i Newspaper says that Sunak is the favourite for No10 after "big-name Tories desert Boris Johnson". It says Mordaunt's allies believe she can now pick up the support of Johnson's supporters to stay in the race.

The Guardian says that Johnson struggled to get the backing of enough Conservative MPs after "more senior party figures cautioned that a Johnson comeback would lead to chaos and an early election".

Image source, The Times

Image source, i Newspaper

Image source, Guardian

Penny Mordaunt remains in the race to be the country's next PM, a campaign source has told the news agency PA Media.

"Penny is still running to be the leader of the Conservative Party.

"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 onto the seats the Conservative Party gained in 2019," the source said.

"Ed Balls [former Shadow Chancellor], shadow cabinet ministers and Labour advisers have all said Penny is the candidate Keir Starmer fears the most," the source added.

Image source, Getty Images

Rishi Sunak has just publicly praised Boris Johnson for his achievements in Downing Street.

In a tweet, external, Sunak wrote: "Boris Johnson delivered Brexit and the great vaccine roll-out.

And Sunak - who is now seen as a favourite to be the next PM - added: "Although he has decided not to run for PM again, I truly hope he continues to contribute to public life at home and abroad."

Conservative MP David Morris, who was backing Boris Johnson in the leadership contest, tells the BBC he is stunned by the former PM's decision not to run again.

"I was on the meeting with Boris and team not so long ago - within the past hour. And I have got to say that I was absolutely flabbergasted. It's just one of those occasions where you just don't believe it is really happening," the MP for Morecambe and Lunesdale says.

"However, look - I'll say like it is. It's time for the grown-ups, time for backing Rishi. I backed him last time. I've got loyalty to Boris Johnson. And you've got to go with where your heart is.

"I think Rishi will be a fine prime minister," Morris adds.

Boris Johnson announced he would not be standing in the leadership race at around 9pm this evening.

At the same time, Penny Mordaunt retweeted a link to her article in the Telegraph, external where she outlined how she would govern as the next prime minister.

“Only a unified, disciplined and honest government will earn the trust of voters at the next general election and I will deliver this,” she writes.

Image source, PA

Image source, PA Media

Cabinet minister Nadhim Zahawi has said he is now backing Rishi Sunak in the Tory leadership race, after only publicly announcing support for Boris Johnson this morning.

Moments before Johnson made his announcement, an article was published in the Telegraph written by Zahawi titled: "Get ready for Boris 2.0, the man who will make the Tories and Britain great again."

However, the article is no longer available and link the to the web address reads: "404 – Sorry, page not found."

Zahawi tweeted, external: "Given today's news, it's clear that we should turn to Rishi Sunak to become our next prime minister.

This morning, Zahawi said Johnson had "got the big calls right, whether it was ordering more vaccines ahead of more waves of Covid, arming Ukraine early against the advice of some, or stepping down for the sake of unity."

He said: "Britain needs him back. We need to unite to deliver on our manifesto.”

Image source, Getty Images

The Liberal Democrats say the Conservative leadership contest has become "a total farce".

“This is a humiliating climbdown for Boris Johnson and all the Conservative MPs who wanted to put him back in Number 10," Lib Dem Deputy Leader Daisy Cooper says.

She says the public will "rightly be furious that they’re set to endure a third Conservative PM in just as many months".

“While people are struggling with their spiralling bills, the Conservatives look set to appoint a former chancellor who lost the country billions," she says.

She reiterated calls for a general election, saying the country doesn't need "another Conservative coronation".

A source close to Rishi Sunak tells the BBC's Nick Eardley: "We are not taking anything for granted.

"Rishi will be continuing to talk to colleagues tomorrow morning before nomination papers go in, and discussing how best to unite the party and take the country forward."

You can track which MPs have backed which candidate so far by clicking here., external

Nick Eardley
Chief political correspondent

This is a huge development. I’ve been on the phone tonight to Boris Johnson backers and they were convinced he’d stand. Tonight, confirmation he won’t.

In his statement, Mr Johnson says he thinks he could have won the membership and been in Downing St by Friday. But he concedes he would struggle to unite his party in parliament.

The former prime minister says he got 102 backers. We can’t verify this, the public number is lower and we may never know for sure. It’s safe to say many MPs are sceptical he had the number his campaign says.

This all makes Rishi Sunak the firm favourite. But Penny Mordaunt will be trying over the next few hours to win over Mr Johnson’s backers and show she has a significant chunk of Tory MPs behind her.

Expect opposition parties to pounce on the fact Johnson said he was "uniquely placed to avert a general election now".

And here is the former PM's statement in full - he claims to have reached 102 backers although only 57 MPs had publicly declared their support for him.

Image source, Reuters

More from Boris Johnson who has just announced he will not stand to return to lead the Conservative party.

He says he is "well placed" to deliver a victory in the 2024 general election.

In his statement outlining his reasons behind the decision, he writes: "Tonight I can confirm that I have cleared the very high hurdle of 102 nominations, including a proposer and a seconder, and I could put my nomination in tomorrow".

The BBC has not been able to verify this figure as only 57 MPs had publicly declared they had backed him.

The former PM adds: "There is a very good chance that I would be successful in the election with Conservative Party members - and that I could indeed be back in Downing Street on Friday.

"But in the course of 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."