Tom Tugendhat and Penny Mordaunt are among names who have been tipped to succeed Ben Wallace as defence secretary.
Mr Wallace announced plans over the weekend to resign at the next Cabinet reshuffle and stand down as an MP at the next general election.
Mr Tugendhat, the security minister and former Territorial Army officer who served in Iraq and Afghanistan, is being discussed by Conservatives MPs as a possible replacement.
Allies told The Telegraph that the Tonbridge and Malling MP would be the “natural successor” to Mr Wallace.
He previously chaired the foreign affairs committee and was a former Tory leadership hopeful.
Other candidates to replace Mr Wallace are understood to include Commons Leader Ms Mordaunt.
The Portsmouth North MP, who was a Royal Navy reservist, has briefly held the role before.
But Ms Mordaunt, who stole the show at the King’s Coronation with her sword-wielding, may not be handed such a high-profile position by No 10 after running against Rishi Sunak for the Conservative Party leadership.
Foreign Secretary James Cleverly, an Army reservist, is also believed to be a favourite for the role.
Other names include Foreign Office minister Anne-Marie Trevelyan and ex-justice secretary Brandon Lewis, who has reportedly been approached about a return to the Cabinet.
Mr Wallace is said to favour armed forces minister James Heappey, who is his deputy in the Ministry of Defence.
Mr Sunak’s close ally John Glen, who is chief secretary to the Treasury, has also been linked to the role.
It is a key position for Mr Sunak to fill given Russia’s ongoing invasion of Ukraine.
Mr Wallace is believed to have told the PM on June 16 of his plans to stand down from Cabinet.
He told The Sunday Times he would stand down as an MP at the next election but ruled out triggering another by-election for the Conservatives to battle.
Mr Wallace, who survived three prime ministers in his current role, played a key role in the UK’s response to Russia’s invasion of Ukraine and was a close ally of Boris Johnson.
His Wyre and Preston North constituency will disappear at the next election after boundary changes and he said he would not seek a new seat.
He said: “I went into politics in the Scottish Parliament in 1999. That’s 24 years. I’ve spent well over seven years with three phones by my bed.”
Mr Wallace had expressed an interest in standing for the position of Nato secretary-general but his bid was not backed by US President Joe Biden.
