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.

Foreign Secretary Liz Truss and trade minister Penny Mordaunt are widely expected to run, as are former health secretaries Sajid Javid and Jeremy Hunt.

Wallace said his decision wasn’t “an easy choice to make, but my focus is on my current job and keeping this great country safe.”

Conservative party officials on Monday are expected to set out the timetable for a leadership contest, with the aim of having a winner by the end of the summer. The two-step process involves Tory lawmakers voting to reduce the field of candidates to two, who will then go to a ballot of all party members — about 180,000 people.

The winner of the vote will become both the leader of the Conservative party and Britain’s next prime minister, without the need for a national election.

Johnson’s resignation marked the end of three tumultuous years that saw the divisive leader fend off numerous scandals and a Conservative leadership challenge. For months, he managed to cling on to power despite allegations that he protected supporters from bullying and corruption allegations, and that he misled Parliament about government office parties that broke COVID-19 lockdown rules.

But his handling of allegations about a senior politician who had been accused of sexual misconduct proved the last straw for many Conservatives, who this week openly revolted and forced him out of office.

Johnson remains in office to head a caretaker administration, but many Conservatives don’t want a lame-duck leader — especially amid a worsening cost-of-living crisis triggered by soaring food and energy prices.