Former health secretary Jeremy Hunt is considering a Tory leadership bid as the race to succeed Boris Johnson heats up following his dramatic resignation.
Allies claim Mr Hunt is attracting a lot of support from Tory colleagues.
Senior backbencher Tom Tugendhat and Attorney General Suella Braverman have already announced plans to stand.
Mr Johnson was forced out as Tory leader after a cabinet revolt over his leadership but wants to stay on as PM until the party chooses a successor.
Opposition parties and some Tories want him to go now – but that appears unlikely to happen and prime ministers have stayed on during leadership transitions in the past.
He has appointed a new cabinet line-up, replacing ministers that resigned in protest at his leadership, and has told them he will not ask them to make major policy decisions until a new leader is in place.
Sir Geoffrey Clifton-Brown, the treasurer of the 1922 Committee of backbench Tory MPs, said in an “ideal world” deputy PM Dominic Raab would take over for a few weeks but “that ship has sailed”.
“We must now live with the fact that Boris Johnson will be prime minister until a successor can be voted on,” Sir Geoffrey added.
A timetable for the Tory leadership race is due to be confirmed next week and the new prime minister is expected to be in position by September.
The Labour Party has threatened to try and unseat the PM immediately through a vote of no confidence, although this would need considerable support among Conservatives to succeed.
Labour’s Deputy Leader Angela Rayner told the BBC “the fact he’s trying to cling on for the next couple of months is completely unacceptable”.
Mr Hunt urged Tory MPs to oust the prime minister in a party confidence vote last month but has not publicly commented on his leadership ambitions since Mr Johnson quit as party leader.
A former health and foreign secretary, Mr Hunt ran for the Conservative leadership in 2019 and made the final two, before being beaten by Mr Johnson in the ballot of party members.
Tom Tugendhat biographical details
The chairman of the Commons foreign affairs committee, Mr Tugendhat, launched his leadership bid by writing in the Daily Telegraph on Friday, promising tax cuts and “new energy and ideas” for government.
“I have served before – in the military, and now in Parliament. Now I hope to answer the call once again as prime minister,” said the former soldier, who has been a prominent critic of Mr Johnson.
Attorney General Ms Braverman has already confirmed she will stand, while former Brexit minister Mr Baker said he was “seriously” considering running after being asked by people to do so.
Suella Braverman biographical details
Former Health Secretary Sajid Javid and Transport Secretary Grant Shapps – who both revolted against Mr Johnson – are also considering leadership challenges.
So too is Defence Secretary Ben Wallace, a bookmakers’ favourite who is said to be taking soundings from Tory colleagues.
In a tweet, Mr Wallace addressed speculation “I’m going to be next prime minister” by jokingly sharing a picture of an American former basketball player who shares his name. “I’d vote for you!,” Mr Wallace wrote.
Meanwhile Conservative MPs Rehman Chishti and John Baron have told the BBC they were thinking about running for leadership of the party.
“We need leaders who best reflect modern Britain and can provide solutions to the challenges our nation is facing now,” said Mr Chishti, a former barrister and UK trade envoy to Pakistan.
In what could be a big field of candidates, other Tory MPs tipped to run include:
Foreign Secretary Liz Truss
Former Chancellor Rishi Sunak
Home Secretary Priti Patel
Trade minister Penny Mordaunt
Business Secretary Kwasi Kwarteng
More declarations are expected in the coming days, but some senior Tories have already said they will not be running, including former Levelling Up Secretary Michael Gove, Deputy Prime Minister Dominic Raab and former Health Secretary Matt Hancock.
It may not surprise you to discover that Westminster is a postcode which doesn’t suffer a deficit of ambition.
The wannabes will fight a popularity contest among Tory MPs in the next few weeks, and should two of them be left at the end of that process, Conservative Party members will get the final say over the summer.
Somewhere between 100,000 and 200,000 people will be charged with selecting the next head of our government on our behalf.
It is a safe bet the next prime minister will be a very different character to Boris Johnson. Given the manner and motivations behind his toppling, being seen to ooze integrity and revere truth are qualities all the candidates will aspire to illustrate.
But beyond that there will be an intriguing debate about what it means to a Conservative in 2022.
When a new leader assumes office, the political landscape will instantly shift.