Defence Secretary Ben Wallace on Friday said he would not run to be Britain's next prime minister.
Instead, he said he was leaning towards supporting a sensational comeback by former Conservative leader Boris Johnson.
He made clear he wanted to remain at the Ministry of Defence and would expect the next leader to invest in Britain's armed forces.
Former soldier Mr Wallace is popular with the Tory grassroots and was widely praised by colleagues regarding him as calm and competent in his handling of the war in Ukraine.
But he stayed out of the summer leadership contest won by Liz Truss, allowing him to remain politically unscathed and in his defence post.
After Ms Truss resigned, he said on Friday that his reasons for not standing last time had not changed.
Mr Wallace told Sky News: "I feel that I can add the best value in keeping people safe at defence, by being the Defence Secretary. It's the job that I have been doing and it's the job I intend to stay doing."
"This will be potentially our third prime minister since the general election of 2019. We have to think about that legitimacy question that the public will be asking themselves, and also about who could win the next election.
"At the moment, I would lean towards Boris Johnson."
Potential candidates to replace Liz Truss - in pictures
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British Prime Minister Liz Truss has resigned from her position. Here, 'The National' takes a look at the candidates vying to replace her, including former Chancellor of the Exchequer Rishi Sunak, above. PA -
Britain's Leader of the House of Commons Penny Mordaunt. AFP -
Former Prime Minister Boris Johnson. Reuters -
Former Home Secretary Suella Braverman. EPA -
Britain's Defence Secretary Ben Wallace. AFP -
Current Chancellor of the Exchequer Jeremy Hunt. PA
Mr Wallace said the former prime minister had "questions to answer" about the ethics scandals that brought him down, but said Mr Johnson had a track record of investing in defence.
He said he would listen to what Rishi Sunak, another potential candidate, had to say about defence and security.
"I will be looking to all candidates to recognise that you cannot have economic security at home without national security," Mr Wallace said.
"This requires real investment for our armed forces and intelligence agencies."
Mr Wallace is the most senior Tory minister so far to express a preference in the looming leadership race.
No candidate has formally declared, but Mr Johnson and Mr Sunak were already piling up endorsements on Friday. Some MPs said they would support Cabinet minister Penny Mordaunt.
The process is being compressed into eight days so that Ms Truss's successor is in place before a much-anticipated fiscal statement on October 31.
