A Conservative Party leadership election is triggered if the leader resigns or loses a vote of no confidence held by the 1922 Committee of Conservative MPs.
Conservative Party MPs can initiate a no confidence vote in the Prime Minister when 15% (48 MPs) of Conservative MPs write to the party’s 1922 Committee Chair, currently Graham Brady MP.
This vote is then scheduled by the chair in consultation with the party leader. This can happen quickly. For example, the recent confidence vote in Theresa May was held on the 12 December, the day after she was informed that the 15% threshold had been reached. MPs then vote in support or against the leader.
If more than 50% of all Conservative MPs vote in support (158 MPs) of the Prime Minister, they can stay as party leader and no new vote can be triggered for 12 months. They remain as Prime Minister.
If the Prime Minister lost the confidence vote among Conservative MPs, they would not be able to stand again. But any other candidate could stand in a new leadership contest.
There is no other formal method by which to initiate a leadership challenge. However, there are ways for the rest of the party to express a lack of confidence in the leader.
The National Conservative Convention (NCC) is a body representing the voluntary wing of the party, made up of association chairs, area and regional officers and specialised groups (such as Young Conservatives and the Conservative Women’s Organisation). In April 2019, more than 65 Conservative Association Chairmen signed a petition calling for an extraordinary general meeting of the NCC. This was significant as it passes the threshold required to hold an extraordinary general meeting as laid out in the Conservative Constitution.
A non-binding vote of no-confidence will be held at the extraordinary general meeting of the NCC in June, which could put further pressure on the Prime Minister to resign the leadership.
If a Conservative prime minister resigns as leader, this triggers a contest for a new leader. They can remain as Prime Minister while a new leader is sought.
If they resign as Prime Minister, they can remain leader until a new leadership contest. It is modern convention that a prime minister is party leader but in the past the two posts have been held by separate people. It would depend on the Queen accepting the recommendation for who should take over as Prime Minister.
The election takes place in two stages. In the first stage (shortlisting), Conservative MPs put their own names forward. In the 2016 leadership election they also needed the nominations of two other MPs to be allowed to stand.
MPs then vote in a series of rounds to whittle down the candidates. In each round, the person with the fewest votes is removed. This continues until there are only two candidates remaining. Then, in stage two, the party membership is balloted on which of the two candidates they prefer.
The timescale for each contest is set out by the 1922 Committee. In 2016, the whole process was scheduled to take two months, but this time was not needed after Andrea Leadsom withdrew following the second ballot and Theresa May became leader. The process could be shortened to one month.
The rules by which the 1922 Committee (a committee representing backbencher Conservative MPs) arranges votes of no confidence and the first stage of Conservative leadership contests are not published. They can also be changed at any time by the 1922’s Executive Committee (in consultation with the Conservative Party Board, which is made of representatives from each section – voluntary, political and professional – of the party). This means, for example, that the rule that means a new vote of no confidence cannot be triggered for 12 months could be removed with little to no notice.
The second stage is guided by the Conservative Party Constitution – changes to this must be decided by the Constitutional College of the Conservative Party, which is an electoral college made up of the National Conservative Convention (representatives of the voluntary wing), MPs, MEPs and the representatives of Conservative Peers. However, the exact rules for the conduct of the ballot are decided by the Conservative Party Board and the Executive Committee of the 1922 Committee.
This is unclear – unlike the Labour Party, the Conservative Party Constitution has no rules on what should happen if a leader were to become permanently unavailable.
If the Prime Minister lost a leadership challenge, they would not automatically resign from the post.
They could choose to stay as Prime Minister until a new leader is elected or resign in favour of another Conservative MP who would temporarily be Prime Minister until the leadership contest is over. This would be an unusual situation.
The UK has de facto caretaker governments during general elections but not during leadership challenges. So the Government and the civil service functions without change.
A temporary Prime Minister during a leadership contest would still have all the powers of the Prime Minister but would be in a difficult position.