Rishi Sunak officially joins race to be U.K. prime minister

It is the second time in less than four months that Sunak, 42, has vied for the role. Over the summer, the former U.K. chancellor made it to the final round in the race to succeed Boris Johnson before losing to Truss when the vote was put to party members.

Sunday’s announcement makes Sunak the first — and, so far, the only — formally declared candidate to have collected the 100 nominations from fellow lawmakers required by 2 p.m. Monday to appear on the party’s ballot, according to public tallies. If more than one candidate passes the threshold, members of Parliament will select two to be put to an online vote by party members, with the results expected Oct. 28.

As of Sunday, Sunak’s strongest challenger appeared to be Johnson, the former prime minister whose forced resignation this July kicked off Britain’s current bout of political chaos. In his resignation from Johnson’s cabinet, which prompted a wave of others to quit and ultimately forced Johnson to resign, Sunak said the public deserved a government that conducted itself “properly, competently, and seriously.”

On Saturday, reports in British media said the two men — who once worked side by side — were holding late-night talks, prompting speculation that the two could strike a deal to put their rivalry aside and join forces once again on a joint ticket.

Adela Suliman and Karla Adam contributed to this report.