According to his campaign, Rishi Sunak has received the 100 MP nominations required to run for Conservative leader and Prime Minister.
After losing to Liz Truss in the summer, the former chancellor has yet to say whether he will run again for the job.
Boris Johnson is returning to the United Kingdom, as supporters rally behind his potential comeback.
Penny Mordaunt is the only candidate who has formally launched a campaign.
The hopefuls have until Monday at 14:00 BST to find 100 backers. If three candidates reach the threshold, Conservative MPs will eliminate one in a ballot on the same day.
MPs will vote on “indicative” ballot of the final two, with the winner determined by an online vote of party members, which will conclude next Friday.
Polling suggests that Mr. Johnson, who was ousted from office three months ago by his own MPs, would be the favorite to win a members’ vote.
According to the BBC’s running total, he has 44 declared supporters so far, though other sources suggest that number could be higher.
Mt Johnson is set to return to the UK after a Caribbean vacation, and supporters are hoping he will launch a campaign to return to Downing Street.
Sir James Duddridge, a close ally, said he received a message from the former PM saying: “Dudders, I’m flying back. We’re going to do it. I’m willing to participate.”
Tobias Ellwood, another supporter, stated that he was the 100th MP to back Mr. Sunak, adding, “Time for centrist, stable, fiscally responsible government offering credible domestic and international leadership.”
His supporters claim he is the only candidate who will have the support of the voting public after winning the 2019 general election. Mr. Sunak has received backing from a number of senior colleagues, including former chancellor and health secretary Sajid Javid, Security Minister Tom Tugendhat, and former health secretary Matt Hancock, despite the fact that Mr. Johnson is still under investigation by Parliament over whether he lied to MPs about Party gate.
