Senior Tories have warned Boris Johnson he does not have the support among Conservative MPs to launch a leadership challenge that could destabilise the party and spark an election letting Jeremy Corbyn into Downing Street.    

One cabinet level source told The Independent “no one is going to back Boris” if his recent moves to publicly impose his will on Brexit end up strengthening the Labour leader.

Another senior supporter of Chancellor Philip Hammond accused the Foreign Secretary of trying to set himself up for a “self-righteous resignation” from the front bench.

Even prominent Brexiteers said that while they were glad Mr Johnson is pressuring the Prime Minister, they believe the best option for delivering stability and Brexit is to keep Theresa May in post until after EU withdrawal.

It follows days of sniping between Mr Hammond’s allies and those of Mr Johnson, and revelations that both were among ministers plotting to remove Ms May after the election.

Mr Johnson, in particular, wrote a 4,000-word article setting out his Brexit vision shortly before Ms May was to give her own major speech. After she delivered it, he is said to have set out redlines in a bid to control the Government’s position, with allies claiming he had blocked Mr Hammond from securing a longer Brexit transition period.

It led to speculation Mr Johnson will launch a bid to unseat Ms May, which other MPs fear could mean an election just as Labour and Mr Corbyn are becoming more popular with the electorate.

The cabinet level source said: “No one is going to back Boris if Jeremy Corbyn is strengthened by his nonsense. There is not going to be an imminent leadership bid from Boris, the support isn’t there.

“The truth is that Boris is just floating ideas for Brexit backing MPs, to see what sticks, seeing who supports it and then trying to make a point of championing it.

“But it’s destabilising, the result could be a snap election. No one wants that. But that is the threat of him going for the leadership.”

A prominent Brexiteer said he thought Mr Johnson’s interventions in the Brexit debate could have “saved Ms May” from doing something that would anger Leave backing MPs.

But when it came to the question of the leadership, he said: “People who back Brexit will stick with Theresa May because at the moment she is doing the right thing for Brexit.

“Her speech was a political solution, there was something for everyone and it held the party together. Boris was just frustrated that his stock was slipping if he didn’t do anything. At the same time what he did do stopped the PM following Hammond too much.”

Ms May had managed to temporarily unite her cabinet behind her Florence speech, which called for a two-year transition in which the UK would continue to pay into EU coffers, remain a part of the single market and customs union and retain free movement.

But another senior Tory source, who backs Mr Hammond, said MPs are still “furious” that the truce failed to last 48 hours due to Mr Johnson’s intervention.

“He’s lining himself up for a self-righteous resignation,” the MP said.

“The way it works is that he sets himself up as the heart and head of the Brexiteers. Then he starts setting out red lines that are impossible for the Prime Minister to meet.

“Then that means eventually he can say he has no other option but to walk, then he goes to the backbenches to consolidate his position with the Brexiteers. So this is all about burnishing his leadership credentials. His mission is to make sure that when the time does come he is their choice.”

Conservative MPs say there are up to 30 of them willing to sign a letter challenging the Prime Minister’s leadership, with 48 the number needed to spark a vote of no confidence, but one said Mr Johnson was not the focus of their opposition to Ms May.

The MP said: “The names are not on the list because all those people want to create a space for Boris.

“There are those who wanted something to happen after the Grenfell fire disaster, but there are also people on there who say May has got to go, but that she has until 2019 to get the deal.”