Kemi Badenoch plotted with fellow Conservative cabinet ministers to remove Rishi Sunak as prime minister months before the general election, it has been claimed.

Anthony Seldon, who has written political biographies of every prime minister since John Major, has alleged in a new book that Badenoch, who was business secretary at the time, phoned several other cabinet ministers to ask “if anyone was interested in changing the captain”.

An ally of Badenoch, who is now the Conservative leader, described the claim as “total bollocks”.

The book about Sunak’s time as prime minister, which is being serialised in the Independent, says Badenoch did not respect Sunak, who she believed had been rude to her. Citing a series of sources, it says she sought to oust Sunak in 2023, when he faced considerable internal pressure over migration policy.

It quotes one Conservative MP, who the book says is now a member of Badenoch’s frontbench team, as saying she was “a menace who orchestrated trouble in the cabinet” under Sunak.

The book, titled Sunak at 10: The Last Conservative PM?, cites another unnamed “insider” as saying Badenoch “was actively looking at bringing Sunak down, constructing imaginary cabinets and offering jobs”.

After Robert Jenrick resigned as immigration minister in December 2023 over the details of Sunak’s plan to deport asylum seekers to Rwanda, the book says Badenoch discussed telling Sunak she would resign from the cabinet if he did not amend the policy, with some people recounting that Badenoch “had promised she would ‘take him out’”.

It was at this point, the book says, that Badenoch contacted other cabinet ministers to see if any wanted a change in PM. It says she wanted “to avoid the image of wielding the knife”.

Danny Kruger, a then Conservative MP who, like Jenrick, has since defected to Reform, told Seldon that Badenoch “definitely wanted” to remove Sunak and replace him “but was concerned about being a fag-end prime minister” given the looming election.

Seldon says in the book that Badenoch decided against any challenge because she thought this would lead to her being blamed for an election defeat. It also says another reason for caution was Badenoch’s worry that she might lose a leadership contest to Penny Mordaunt, the then leader of the Commons.

The book says the plotting prompted Sunak to condemn what he called “attention-seeking” rebels and he told allies: “They probably want me to tell them to fuck off so they can pontificate, but I have a country to run. I’m not going to rise to the bait.”

Sunak said the impression of plotting and infighting pushed down the Tory vote and made the eventual election defeat in July 2024 even worse.

Badenoch was in the cabinet throughout Sunak’s time as PM, first as trade secretary and then business secretary. She had stood to become Conservative leader in the 2022 internal party contest after Boris Johnson announced he was stepping down, finishing fourth behind Liz Truss, Sunak and Mordaunt. Sunak became prime minister without a contest after Truss’s premiership imploded in just 45 days.

After the general election defeat, Badenoch became Tory leader, beating Jenrick in a vote of Conservative members.

Dissatisfaction with Sunak was far from uncommon among Conservative MPs and ministers as the party headed towards what was seen as an inevitable election defeat, even if most accepted he had inherited a near-impossible situation.

There was little appetite for yet another change of leader, however, which would have brought about a sixth Conservative prime minister inside eight years.

Sunak’s office was contacted for comment.