Nadine Dorries is to stand down as culture secretary following Boris Johnson’s departure from No 10.
Sources close to Ms Dorries – who was a prominent supporter of Liz Truss during the leadership election – said she believed it was the right time to go.
It is understood she was given the opportunity to carry on in cabinet but had chosen instead to return to the backbenches.
It is expected that she will now be given a peerage in Mr Johnson’s resignation honours list, triggering a by-election in her Mid Bedfordshire constituency.
Penny Mordaunt, the former international development secretary, who was an early favourite in the Tory leadership race, is being considered to take over the top job in the Department of Culture, Media and Sport (DCMS), according to reports.
Ms Dorries did not intend her resignation to be taken as a swipe at the incoming prime minister, one friend told the Mail.
“Nadine has agonised over this as she is 100 per cent supportive of Liz. But she has decided now is the right time to leave cabinet,” they said.
Ms Truss will start announcing her cabinet on Tuesday after being formally appointed prime minister by the Queen at Balmoral.
She is expected to settle in to her premiership with a reshuffle and already has some gaps to fill after the resignation of Priti Patel, the home secretary, and Nigel Adams, a Cabinet Office minister.
The departure of Ms Dorries from DCMS leaves several big cultural questions hanging for the new government.
The forthright Liverpudlian threw herself headfirst into the so-called “culture wars”, attacking the BBC for alleged “groupthink” and social media platforms for supposed left-wing bias.
The long-term future of the BBC remains in question, with a government review of the public broadcaster’s funding model thrown into doubt after Mr Johnson’s resignation.
Ms Dorries’s plan to privatise Channel 4 has not been finalised and programme production companies called on Ms Truss to rethink the move.
In recent months, Ms Dorries came to be known as Mr Johnson’s most loyal supporter. She refused to agree with the scores of ministers who resigned to force him from office and days ago said he was the most successful prime minister in a generation.
“He gets the big decisions absolutely right … I think we’ll regret removing him as our prime minister,” she told BBC Newsnight.
She was criticised by many of her colleagues for vicious sniping during the early days of the Tory leadership race.
A tweet in which she attacked Rishi Sunak for wearing expensive clothes, and praised Ms Truss for her cheap earrings, was held up as an example of the bitterness that marked the start of the six-week contest.
A successful novelist who has sold more than 2.5 million copies, her departure from government is expected to enable her to return to writing books.