This is how a Conservative leadership contest works
Theresa May will face a confidence vote from her MPs on Wednesday night
Theresa May could soon be ousted from her position as Tory leader and prime minister as she will be subject to a Conservative party vote of confidence tonight.
Under party rules, if 15 per cent of Tory members of parliament write to the chairman of the backbench 1922 committee expressing no confidence in their party leader then a ballot is triggered.
On Wednesday morning, Sir Graham Brady, chairman of the 1922 committee, announced that this had happened. He said: “The votes will be counted immediately afterwards and an announcement will be made as soon as possible in the evening."
The ballot will be held between 6pm and 8pm, Brady added, with votes counted "immediately afterwards and an announcement will be made as soon as possible."
How does the confidence vote work?
All serving MPs for the Conservative Party will now be able to cast a vote either for or against May. The prime minister will need the backing of at least 158 of them to survive.
If she wins the ballot then she will remain in charge of the party and the country and another contest cannot be triggered for the next 12 months.
However, if May loses the vote, then Graham Brady will invite nominations for her replacement. Candidates for leadership must be nominated by two Conservative MPs and May would be barred from participating as a candidate.
How does a leadership contest work?
MPs then vote on the list of candidates in secret. The vote repeats in quick succession - every Tuesday and Thursday. Each time the politician with the lowest number of votes is removed until just two candidates remain.
From there, people who have been members of the Conservative Party for more than three months receive a postal vote to choose a leader out of the two. When Theresa May became prime minister in 2016 this process was avoid as Andrea Leadsom dropped out of the two horse race, leading to May being the only remaining option.
The last time such a ballot took place was in 2005, when David Cameron and David Davis spent over a month competing for Conservative members' support, before Cameron was announced the winner. Although with the Brexit deadline being in March, it is unclear whether this process would be streamlined.
What is the 1922 committee?
Formally known as the Conservative Private Members' Committee, the committee is made up of Tory backbenchers who meet weekly to speak independently of the party's frontbenchers.
For the last eight years, the committee has extended open invitations to Tory frontbenchers, though its executive membership and officers are restricted to backbenchers.