Boris Johnson: How electrifying moment in parliament and fuming Tory MPs show toxicity towards PM is spreading throughout the party

An absolutely extraordinary PMQs.

Millions of people tuned in last week across various channels to watch the prime minister give an explanation of that party in No 10 on 20 May 2020.

Today, people were no doubt watching to see how he would perform amid building rumours there could be a no-confidence vote against him triggered by his own backbenchers.

Follow live partygate updates as high profile Tory calls for PM to go

I should stress that no one really knows if - and when - that threshold of 54 letters to trigger a ballot will come (apart from the keeper of the list Sir Graham Brady), although the mood in the party now seems to be crystallising that he won't be the man to lead them into the next election.

As one Conservative political operative put it to me on Wednesday: "Johnson won support because he could reach a wider base of voters as the Heineken politician who polled better than the party, but now he is a drag anchor on colleagues so it really is a question of when not if."

Infuriated by that television interview on Tuesday when the prime minister told the country "nobody told me" the No 10 event was breaking the rules, some from the 2019 intake have been openly discussing putting letters in en masse - the so-called pork pie plot (named as one of the ringleaders, Alicia Kearns, represents Rutland & Melton) - in the past 36 hours, heaping pressure on an already imperilled PM.

This then context in which the PM came to PMQs, the opening of which dealt him the first of two material body blows as the Conservative MP for Bury South Christian Wakeford opened the session by defecting to the Labour Party.

Sir Keir Starmer was beaming, Mr Johnson's benches fuming with colleagues shocked and incensed by this defection. But that a Tory MP and former councillor crossed the floor to the Labour benches - that is extremely difficult for any PM.

Labour party sources are telling me this is Operation Domino implying there is more to come, while Tory sources suggest Mr Wakeford's shock defection helped the PM, in the short term at least, prompting some to perhaps reconsider putting letters in as tribal politics kicked back in.

"It's like when you're arguing over the dinner table and then a suicide bomber walks into the dining room. It sort of puts it all into perspective," observed a rebel of the shift in colleagues' mood.

But there was a second body blow during the session on the Commons today when Tory grandee and former cabinet minister David Davis became the first Conservative MP to tell the prime minister to go in an electrifying moment.

A Labour operative sent me a tweet - dated 2018 and linked to Brexit - from a Johnson loyalist Nadine Dorries minutes after the former cabinet minister made his move: "David Davis is ex SAS. He's trained to survive. He's also trained to take people out."

These two painful bookends to PMQs - despite the PM showing some fight - speak to the precariousness of his position.

The uncertainty in Westminster is crippling, and the mood has been toxic. There is talk that Mr Wakeford was sent over the edge by whips threatening the future of his seat with boundary changes.

One rebel told me that the briefing, backbiting and bullying was only serving to harden resolved and deepen splits.

"The excessively aggressive approach from No 10 is not helping. They are like a rabies-ridden dog that's been cornered and is lashing out."

The business of government is on hold as everyone watches and waits. I'm told that a group of the 2019 intake are still ready to put in letters, resigned to the reality that Mr Johnson is more likely to lose them their seats than save them in the next election.

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As one MP put it to me: "It's all planned out and a question of when. We don't want the new leader to take a hit at the local elections [in May]. So we may well wait unless the Sue Gray report really hits."

But the fevered speculation that a confidence vote could be imminent has now again been replaced with anticipation of what the Sue Gray report will conclude.

What comes next is a very open question.

Tonight I'm told that the 1922 backbench committee is considering changing the rules around triggering a no-confidence vote to give the party more flexibility to try to oust the PM if they so choose.

Under current rules, MPs cannot trigger a ballot for 12 months if a sitting PM survives a confidence vote. Under new proposals, MPs could introduce a 'super trigger' which could allow MPs to call a second ballot within a year if a bigger proportion of MPs (perhaps a third) back it.

But the real question now is whether Boris Johnson, however hard he fights, can secure his political future beyond a stay of execution.

Some of his cabinet supporters are convinced he can, with one cabinet minister telling me on Tuesday night that he's going to face an incredibly bumpy four weeks but can make it to the other side. He's buying for time.

If he can survive the Sue Gray report and MPs decide to wait until after the May elections to trigger a vote, can he use that time to repair the devastating damage that the 'Partygate' scandal has caused?

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The defection and the David Davis denouncement on Wednesday appears to have shaken Conservative MPs and might have bought Mr Johnson a little bit of breathing space.

But those dramatic interventions on Wednesday from a member of the old guard and the new points to the toxicity that is now spreading towards Boris Johnson throughout his parliamentary party.