Boris Johnson was fighting on Sunday to get enough support to make a shock return as Britain's prime minister after prominent figures on the right wing of the Conservative Party coalesced around the man once accused of betraying him, Rishi Sunak.

Sunak, the country's 42-year-old former finance minister, confirmed on Sunday he would enter the competition to replace Liz Truss, vowing to tackle the country's "profound economic crisis" with "integrity, professionalism and accountability."

"I want to fix our economy, unite our party and deliver for our country," said Sunak, the man accused by Johnson's supporters of ending his previous three-year spell in office.