Since Sunak pushed through his Rwanda immigration plan last week, ignoring the demands of several in his party's right wing to toughen it, some have been increasingly vocal in their criticism of the British leader, fearing he has little chance of reducing the opposition Labour Party's lead before the election.

While Clarke is favoured by some on the right wing of the Conservative Party, his calls for a replacement likely not go down well with other more centrist lawmakers, who still hope Sunak can lead them to victory.

In a column for the Daily Telegraph newspaper, Clarke said: "Now is not the time to despair. It is the time to act." He acknowledged that his idea might not be welcomed by all sides of the Conservative Party.

"A change of leadership would not have to be a protracted affair," he said, adding it could take a week.

"We have a clear choice. Stick with Rishi Sunak, take the inevitable electoral consequences, and give the Left a blank cheque to change Britain as they see fit. Or we can change leader, and give our country and party a fighting chance."

(Reporting by Farouq Suleiman and Elizabeth Piper, editing by Kylie MacLellan)