THE Prime Minister was dealt a blow by his own sibling today as Jo Johnson announced that he would be quitting politics and suggested brother Boris was not acting in the “national interest” over Brexit.

Jo Johnson, who is pro-EU and has called for a second referendum, announced that he will be stepping down as Tory MP for Orpington and as universities minister in his brother’s government.

He said he had been “torn between family loyalty and the national interest” and cited “unresolvable tension.”

Mr Johnson is at odds with his older brother, who is gearing up for a possible general election campaign and has vowed to leave the EU on October 31, with or without a deal.

Labour’s shadow education secretary Angela Rayner said: “Boris Johnson poses such a threat that even his own brother doesn’t trust him.”

And shadow policing minister Louise Haigh said: “If your own brother doesn’t believe you’re acting in the national interest, why should the country?”

Boris, in a 2013 interview with the Telegraph, was asked whether there was any rivalry between him and his younger brother in comparison with the Milibands.

He said: “Absolutely not … only a socialist could do that to his brother, only a socialist could regard familial ties as being so trivial as to shaft his own brother.”

In a speech surrounded by police officers today in Wakefield, the Prime Minister said he would “rather be dead in a ditch” than ask the EU for an extension.

As he continued speaking, one of the trainee officers who had been waiting for the PM, who ran more than an hour late, appeared to collapse behind him as though he had fainted.

Mr Johnson’s speech was also blighted by his insistence on reciting the words of the police caution, which he then could not remember.

He was also asked by a journalist: “If your own brother has lost faith in your plan, surely you’re the next person in your family to resign?”

Mr Johnson later looked visibly relieved to be asked about a different topic.

Commons leader Jacob Rees-Mogg has said that the government will mount a fresh attempt to call an early election on Monday.

The government’s bid on Wednesday night to call a general election next month failed to get the backing of two-thirds of MPs.

Opposition parties are in talks about how to respond to Mr Johnson’s call for a snap election, with concern about whether the poll should be delayed until after an extension has been secured to prevent a no-deal Brexit on October 31.

A cross-party bid to require a Brexit extension, dubbed by Mr Johnson as a “surrender Bill,” cleared the Commons on Wednesday and is due to complete its progress through the Lords today.

The fallout continued from Mr Johnson’s decision to remove the Tory whip from 21 MPs, including former chancellors Philip Hammond and Kenneth Clarke, after they rebelled over the plan to block a no-deal Brexit.

Cabinet ministers reportedly raised concerns with Mr Johnson and the One Nation group of Conservatives called for the 21 to be reinstated.

One Nation group leader and former Cabinet minister Damian Green told the BBC: “I’m afraid it does look as though somebody has decided that the moderate, progressive wing of the Conservative Party is not wanted on voyage.”