Theresa May is facing the most serious crisis of her premiership after her foreign secretary and minister in charge of Brexit resigned within hours of each other. David Davis, the Brexit secretary, and his colleague Boris Johnson dramatically quit over what they see as a watering down of the UK's position on leaving the European Union. So what does this mean for the British Prime Minister, and does it mean that Brexit is any more or less likely to happen?
Can Theresa May survive as Prime Minister?
The short answer is yes, but she faces the battle of her political life to do so. May's biggest challenge was trying to resolve a longstanding lack of unity in her government and Conservative Party over Brexit. She thought she had achieved that at a summit of her Cabinet ministers last Friday at her country residence, Chequers. That meeting approved a new Brexit position, anticipating a closer post-Brexit relationship with the EU than previously expected (a position known as a "softer" Brexit).
But it has had the opposite effect, blowing apart divisions over Europe and enraging Brexiteers, as the supporters of Brexit are known. Losing two of the most high-profile pro-Brexit ministers from May's Cabinet will fuel dissent among members of Parliament who are unhappy with the new policy, and in turn destabilize her position as leader of the Conservative Party.
The likelihood of a challenge to her leadership has increased dramatically. It would take 48 Conservative MPs -- out of a total of 316 -- to trigger a confidence vote, which, given the febrile atmosphere at Westminster, is not a high bar. However, as it stands she would likely win that vote, because it is thought more than 159 MPs would back her. In her two years as Prime Minister, May has faced serious challenges and stood firm, so it is very unlikely she would resign of her own accord.
However, the resignation of senior Cabinet ministers over the issue of Europe draws comparisons with Margaret Thatcher's downfall as PM in 1990. Then, Thatcher vowed to fight on, but was later weakened by failing to win outright in the first round of the leadership election and was forced to resign.
How did it come to this?
May took over as Prime Minister two years ago in the wake of the referendum in which the UK public voted for Britain to leave the EU. The Conservative Party was split between those vehemently pro-Brexit and those who had backed remaining in the EU. She tried to unify these two factions by promoting senior figures into powerful jobs, including Johnson at the Foreign Office and Davis in charge of Brexit.
But from the start she struggled to explain what leaving the EU would mean for the UK, and was heavily criticized for saying only that "Brexit means Brexit." In an attempt to reassert her authority over her government and Parliament, she called a general election in June 2017 -- which backfired and she lost her Conservative majority, forcing her to go into an informal arrangement with a smaller, pro-Brexit party from Northern Ireland.
Since then, her authority has been severely weakened by the failure to pin down a clear negotiating strategy with Brussels, who have warned that the UK is in no position to cherry pick on its future trading relationship with the EU. There have been a number of resignations from May's Cabinet over the last year, but until this week they were over personal scandals and issues unrelated to Brexit.
Why did Boris Johnson and David Davis resign?
Both ministers have been threatening, through their allies, that they would quit over Brexit for several months, but this was seen as a tactic to exert more pressure on the Prime Minister not to water down the UK's Brexit position. Some 18 months ago, May said that no deal would be better than a bad deal on Brexit, and this pledge has been used by Brexiteers to hold the PM's feet to the fire.
Only a few weeks ago it seemed as though their side was getting their way. A series of votes in the House of Commons on moves to water down Brexit and give more power to Parliament were defeated. However, the Chequers summit, at which the new Brexit position was introduced, changed everything. Johnson made clear his disdain for the plan by saying it would be like "polishing a turd," while Davis declared he was the "odd man out" on the policy.
Both men agreed to support the deal in principle, under the rule of Cabinet collective responsibility, but remained privately unhappy over the weekend. As more details of the plan were published, pro-Brexit Conservative MPs who were not at the meeting were alarmed that it crossed red lines, including the UK continuing to sign up to EU rules on the free trade of goods within the bloc. As that alarm escalated over the weekend, Davis resigned late on Sunday evening. Johnson followed suit on Monday afternoon.
Will the government fall?
This is unlikely. Despite the chaos currently swirling around the Prime Minister, the Conservative Party will want to maintain as much stability as possible, for fear of allowing the opposition Labour party into government. Even if May were to face a leadership challenge and lose, it is unlikely that the new Prime Minister would risk an election at which the Conservatives would almost certainly be defeated. Labour could trigger a confidence motion in the government, but even though the Tories don't have an outright majority, it is unlikely that the Northern Ireland DUP, which supports the Conservatives in government, would side with Labour and allow the government to fall.
What happens if there is a leadership election?
A leadership election would be triggered if May lost a confidence vote of her own MPs. A contest can also be called by the leader at any time -- as happened under the former PM John Major, Thatcher's successor in the 1990s, who issued a back-me-or-sack-me call in 1995, which he won. The first stage of a Tory leadership contest is fought among Conservative MPs only, in a series of votes until the last two remain. The final two contenders then go onto a ballot of the wider party membership.
What does this mean for Brexit?
Under the terms of Article 50, which was triggered in March 2017, Britain must leave the EU two years later, on March 29, 2019. The current crisis does not change that timetable but it does pose the question of whether the entire Brexit negotiation process could collapse.
Brussels is waiting for the UK to come up with a firm position -- which the Prime Minister had on Friday, yet which is now in doubt following these resignations -- before a final round of talks between representatives of the UK and EU takes place this summer. A final deal on Brexit is supposed to be agreed on with Brussels by a summit in October, although EU officials acknowledge this might now be delayed until December.
The final deal must be approved by votes in the British and European Parliaments. Brexit will still happen, the question is still the same as it has always been -- in what form? If the pro-Brexit faction takes over the Tory leadership, it could mean either a hard Brexit or no deal at all. If May can cling on, she will have to compromise on her current soft Brexit position.