Next Prime Minister: who is eligible to enter Conservative Party leadership race to replace Liz Truss as UK PM

The requirements for participation in the next Tory leadership contest have been set out by Sir Graham Brady, the chairman of the 1922 Committee, which oversees leadership elections within the Conservative Party.

Prime Minister Truss’ announced her resignation from office yesterday (20 October), just six weeks after first taking up the post, following a brief premiership beset by economic instability, Tory in-fighting, the resignation of her top two most senior cabinet members, and allegations of bullying and harassment surrounding a chaotic vote on fracking.

Truss announced during her resignation speech that the race to crown the next Conservative leader will be much less protracted than the summer contest that saw her installed as PM. A winner is expected by the end of next week, and could be called as early as Monday (24 October).

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So who is eligible to be in the running to become the third Prime Minister of the year?

Here is everything you need to know about it.

Who is eligible?

To advance to the next stage of the battle to replace Liz Truss, candidates for the Tory leadership will require nominations from at least 100 Conservative MPs, Sir Graham has said.

Following discussions with the Conservative Party’s board and the executive of the 1922 Committee of Tory backbenchers, which he heads, the MP told reporters that nominations will begin immediately and close at 2 pm on Monday 24 October.

Sir Graham added that any candidate with a realistic prospect of winning should be able to obtain 100 nominations. There are currently 357 Conservative MPs, meaning a maximum of three candidates on the ballot paper for MPs to vote on.

Should only one candidate emerge once the nominations process is complete on Monday, then no further deliberations will be required, and it is likely the Conservatives will be able to crown their new leader there and then.

However, if two candidates remain, the choice will once again be put to Conservative Party members in an online vote, just months after the process was modified due to hacking concerns.

The Tory party chairman said the online membership vote to choose a new leader and the next prime minister will be "secure." Sir Jake Berry, speaking outside Parliament, declined to provide details on the measures in place, but said he was "satisfied" there would be no cyber security risks in the race to replace Truss.

When asked about the safety of the binding online vote, Sir Jake responded: “Without going into the security measures we will take… we are satisfied that the online voting system will be secure.”

Could Boris Johnson return?

There are very few restrictions on which Conservative politicians could throw their hat into the ring in the latest leadership contest - although Liz Truss is excluded, for obvious reasons.

That sets the stage for a possible dramatic return for Boris Johnson, whose time away from Downing Street could be as short-lived as Truss’ time residing there.

The former prime minister is said to be flying back from a holiday in the Caribbean as a potential leadership candidate; at the time of writing, Johnson has not declared his intention to run, but he is believed to have the support of scores of MPs.

Talk of Johnson returning to the top post has been faced with opposition from within the Tory party, including Douglas Ross, who reportedly told the BBC it would be a "disaster." Such a move would be immensely divisive within the Conservative Party, with predictions that some MPs may resign the whip and sit as independents rather than serve under Boris.

But his supporters say he is the only probable prime ministerial candidate who has won a general election and has a mandate from the British people. If he does run, he will very certainly face Rishi Sunak, the former chancellor accused by Johnson’s allies for bringing him down, and House Leader Penny Mordaunt.