A KEY ally of Boris Johnson has backed Rishi Sunak to become the next prime minister in a huge blow to the former prime minister.

Suella Braverman, a staunch supporter of Mr Johnson, has backed his rival to replace Liz Truss in Downing Street.

Ms Braverman, whose resignation as home secretary marked the beginning of the end of Ms Truss’s premiership, has now reversed her support for the former chancellor.

Writing in the Telegraph, she said: “I supported Boris from the beginning.

“But we are now in a difficult position. Unity, stability and efficiency are needed. Rishi is the only candidate who fits the bill and I am proud to support him.”

Ms Braverman added: “Everything needs to change.

“We, as a party, must change. We must provide leadership, stability and confidence to the British people.

“We cannot indulge in parochial or nativist fantasies.

“We need to go beyond ‘Left’ or ‘Remain’, ‘One Nation’ or ‘ERG’, ‘Party Right or Party Left’, ‘Wets’ or ‘Thatchers’. Now we all need to compromise and unite… One person can build this team: Rishi Sunak .”

The move will be a major blow to Mr Johnson, who is seeking the support of the 100 Tory MPs he needs to get on the ballot to become the next prime minister.

Home Secretary Grant Shapps has also backed Mr Sunak in the party leadership race.

Mr Shapps, who served in the cabinet under Mr Johnson, tweeted: “We need someone who can provide stability and proven economic competence in these challenging times and @RishiSunak is that person.

“That’s why I’m backing him in the Conservative leadership contest.”