Defence Secretary Ben Wallace has ruled himself out of the Tory leadership race.
He tweeted: “As the Party starts the process of looking for a new leader, I would like to put on the record that I will not be letting my name go forward as a candidate.
"I am privileged to be the UK Defence Secretary and the current threat requires stability in that office.
“The reasons I gave last time for not standing, have not changed.
Ben Wallace
Ian Forsyth
"I will be looking to all candidates to recognise that you cannot have economic security at home without national security.
"This requires real investment for our Armed Forces and intelligence agencies.”
Among the favourites to replace Liz Truss as Prime Minister are Rishi Sunak, Penny Mordaunt and Boris Johnson.
Other names in the frame include Suella Braverman, who was forced to quit as home secretary by Ms Truss, and International Trade Secretary Kemi Badenoch – both of whom stood in the last contest – although they may struggle to get the 100 nominations required.
Liz Truss resigned as Prime Minister on Thursday
Kirsty O'Connor
And Mr Wallace said he is “leaning towards” Mr Johnson as his choice to replace Ms Truss in Downing Street.
The Defence Secretary pointed to Mr Johnson’s record on defence spending and cited the mandate the former prime minister won in 2019.
Mr Wallace argued that without national security, there is “no economic security,” and said he believes it is “important” that whoever puts themselves forward for the top job indicates that.
But he said he also has to “recognise the issue of the mandate”.
“This will be potentially our third prime minister since the general election of 2019, that means we have to think about that legitimacy question that the public will be asking themselves, and also about who could win the next election – that’s obviously important for any political party at the time,” he told broadcasters.
“So at the moment, I would lean towards Boris Johnson. I think he will still have some questions to answer around, obviously, that investigation, but I know when I was Secretary of State for Defence, he invested in defence, he supported me, he supported the actions this country has taken to keep us safe.”
Under the rules set out by Sir Graham Brady – the chairman of the backbench 1922 Committee – and party chairman Sir Jake Berry, nominations will close at 2pm on Monday.
The first ballot of MPs will then be held between 3.30pm and 5.30pm on Monday – if there are three candidates with the required number of nominations the loser will be eliminated.
Once there are two candidates remaining, an indicative vote will be held so that the party membership know which is the preferred option among MPs.
Members will be able to take part in an online vote to choose their next leader and the country’s prime minister with the contest due to conclude by October 28.
The rules appear designed to encourage the candidate who finishes second to stand aside for the winner, ensuring the new leader has the support of the majority.