LONDON — A British Cabinet minister tipped to be a frontrunner in the Conservative Party’s leadership race ruled himself out of the contest Saturday.

Defense Minister Ben Wallace said after “careful consideration” and discussion with colleagues and family, he will not be running to replace Boris Johnson as Conservative leader and the country’s next prime minister.

Wallace was seen by some as the favorite choice among Conservative party members in what’s shaping up to be a wide open leadership race following Johnson’s resignation announcement on Thursday.

Johnson quit as party leader after months of insisting he would stay in the job despite mounting ethics scandals. He said he would stay on as prime minister until the party chooses his successor.

Newly-appointed Treasury chief Nadhim Zahawi launched his campaign to become Tory leader Saturday, pledging to lower taxes and boost defense spending.

Zahawi’s announcement came a day after former chancellor Rishi Sunak, the best-known of the leadership contenders and regarded as the bookmakers’ favorite to win, launched his bid. Sunak resigned on Tuesday, kicking off a mass exodus of government officials that toppled Johnson.

Transport Secretary Grant Shapps, Attorney General Suella Braverman, lawmaker Tom Tugendhat and former equalities minister Kemi Badenoch have also thrown their hat into the ring, and more announcements are expected over the coming days. — Agencies