Tory MPs have started to endorse prospective prime ministers after Liz Truss's dramatic resignation on Thursday.
Sir Graham Brady, the chairman of the influential 1922 Committee of backbenchers, confirmed the leadership contest will conclude by Friday, October 28. This will allow a new prime minister to be in office in time for the Medium-Term Fiscal Plan on October 31.
While no candidates having officially put themselves forward, MPs are already going public with their favoured contenders for No 10.
Boris Johnson - it is understood he will run
Backers include:
1. James Duddridge
"I hope you enjoyed your holiday, boss. Time to come back. Few issues at the office that need addressing." (October 20)
2. Paul Bristow
"We need an election-winner, and we had an election-winner. I will listen to my constituents, and their message was 'bring back Boris'." (October 20)
3. Stephen McPartland
"Interesting that my inbox is inundated with local people saying we must bring back Boris - will he hear them and put himself forward?" (October 20)
4. Brendan Clarke-Smith
"You don’t know what you’ve got until it’s gone. It’s time for him to return." (October 20)
5. Michael Fabricant
"He's the only MP with legitimacy having been overwhelmingly elected by the country. Without him calls for a General Election will grow." (October 20)
6. Nadine Dorries
"Without him, the clamour for a general election will grow." (October 20)
7. Marco Longhi
"He is the only person that commands that authority given to him by the public at a General Election. He is the only person who can discharge the mandate from the people. Please come back, Boss." (October 20)
8. Andrea Jenkyns
"Boris Johnson has the democratic mandate and won the Conservatives an 80-seat majority." (October 20)
9. Andrew Stephenson
"During the last leadership contest as Party Chairman I received countless emails from Conservative members wanting Boris on the ballot. Constitutionally that was impossible. Now it isn't." (October 20)
10. Christopher Chope
11. Shailesh Vara
12. Shaun Bailey
13. Amanda Milling
14. David Morris
15. Karl McCartney
16. Peter Bone
17. Lia Nici
18. Jane Hunt
19. Trudy Harrison
20. Scott Benton
21. Chris Clarkson
22. Mark Eastwood
23. Sheryll Murray
Rishi Sunak - supporters claim he will run
Backers include:
1. Crispin Blunt
"We must take the only course open to us and rally for Rishi." (October 20)
2. Julie Marson
"Rishi Sunak had my support to be leader over the summer because I feared Liz’s approach to the economy would lead to what did happen." (October 20)
3. Richard Holden
Mr Holden told ITV News that Mr Sunak would run again. (October 20)
4. Angela Richardson
"Having spent the summer supporting Rishi Sunak’s leadership bid, my views on his suitability have not changed. If anything, the past six weeks have brought them even more sharply into focus." (October 20)
5. Stephen Crabb
6. Paul Maynard
7. John Glen
8. Kevin Hollinrake
9. Andrew Bowie
10. Simon Hart
11. Craig Williams
12. Anthony Mangnall
13. Andrew Murrison
14. Dominic Raab
15. Gary Streeter
16. John Stevenson
17. Simon Jupp
18. Steve Double
19. James Cartlidge
20. Bim Afolami
21. Nick Gibb,
22. Alex Chalk
23. Fay Jones
24. Maggie Throup
25. Simon Hoare
26. Edward Timpson
27. Huw Merriman
28. Laura Farris
29. Simon Fell
Penny Mordaunt - considering a run
Backers include:
1. Derek Thomas
"My first choice for Prime Minister is again Penny Mordaunt." (October 20)
2. Maria Miller
Ms Miller tweeted: "PM for PM." (October 20)
3. John Lamont
"She is exactly the kind of calm, cool and collected leader we need right now." (October 20)
4. Damian Collins
"I was proud to support Penny Mordaunt's campaign for the leadership of the Conservative Party this summer, and I hope she stands again now. She has the quality and experience to unite the party and rebuild trust in government." (October 20)
5. Bob Seely
6. Andrea Leadsom
7. Robbie Moore
8. Kieran Murray
9. Craig Tracey
10. Nicola Richards
11. John Penrose
What are the Tory tribes?
Brexiteers
Brexit-supporting MPs on the Right of the party largely supported Ms Truss in the last leadership contest. So far, eurosceptics who backed her - including Michael Fabricant and Andrea Jenkyns - have rowed in behind Mr Johnson.
As well as supporting leaving the EU, many Brexiteers have tough views on issues including illegal migration and the culture wars.
The European Research Group of eurosceptic MPs had 35 members in 2020-21 according to parliamentary records, though it has many more supporters within the party. Mark Francois, the chairman, backed Ms Truss, but has not yet declared who he will support this time round.
One Nationers
The biggest grouping within the Tory Party, the One Nation caucus consists of more than 100 MPs mostly in the centre-ground of the party.
It is led by Damian Collins, a former deputy prime minister, who supported Rishi Sunak in last summer’s leadership contest. Other big beasts on the books include Robert Buckland, the Welsh Secretary; Matt Hancock, the former health secretary; Chloe Smith, the current Work and Pensions Secretary; and Tom Tugendhat, the security minister.
Many members of the group were involved in the ousting of Mr Johnson and subsequently supported Mr Sunak.
Red Wallers
The new clutch of Conservative MPs elected to 'Red Wall' seats across the North and Midlands owed their political careers to Mr Johnson. Elected in the 2019 landslide, they were led by Jake Berry, the chairman of the Northern Research Group, and have a particular focus on ensuring the levelling up agenda is delivered.
Prominent 'Red Wallers' to have declared in the race so far include Brendan Clarke-Smith, the MP for Bassetlaw, who is supporting Mr Johnson, and Richard Holden, the MP for North West Durham, who is backing Mr Sunak. There are 45 'Red Wall' MPs.
Blue Wallers
At the opposite end of the country are the 'Blue Wall' MPs, so called because they are sitting in usually safe Tory seats at threat from the Lib Dems.
The 'Blue Wall' stretches across swathes of the home counties and the South West, and includes some of the party’s biggest beasts including Cabinet ministers.
Jacob Rees-Mogg, the Business Secretary; Dominic Raab, the former deputy prime minister; and Steve Baker, the Northern Ireland minister, all hold such constituencies. There are around 40 Tory MPs in 'Blue Wall' seats.
