With another “meaningful vote” by the House of Commons on her Brexit plan imminent, May won 11th-hour promises of cooperation from the EU regarding the contentious backstop plan, including agreement to a “joint legally binding instrument” that would allow the U.K. to initiate a “formal dispute” with the EU if the bloc were to seek to indefinitely lock Britain into the backstop agreement. In addition, a “joint statement” committed the U.K. and the EU to negotiating a replacement for the backstop agreement by December 2020. Moreover, Britain unilaterally declared that there was nothing that could prevent it from disengaging from the backstop arrangement if negotiations between the EU and the U.K. on an alternative solution were to implode without a reasonable prospect of reconciliation.

In the view of Attorney General Cox, these pledges reduced the risk of the U.K.’s becoming ensnared indefinitely in the backstop agreement, but they did not fundamentally transform the legal status of the agreement. Although the promises garnered additional support for May’s plan when it was put to a vote in the House of Commons on March 12, it still failed, albeit by a lesser margin (149 votes, 391–242) than its earlier rejection by Parliament.

Parliamentary grab of the House of Commons agenda for indicative votes

On March 13 the House of Commons voted 312–308 against leaving the EU without a deal in place. The next day, by just two votes, May survived a vote that would have taken control of Brexit away from her and handed it to Parliament. In a letter to EU leaders on March 20, she requested that the date of Britain’s departure from the EU be delayed until June 30. Ultimately, the EU agreed to delay Brexit until May 22 but only if Parliament approved May’s deal by the week of March 24. That failing, the EU would give the U.K. until April 12 to decide whether to cancel Brexit, leave the EU on that date without a withdrawal agreement, or request a significantly longer delay. That last option would require Britain to participate in elections in May for the European Parliament, a prospect abhorred by hard-line Brexit advocates.

May’s frustration at the failure to have a deal in place for the scheduled March 29 departure deadline came spilling out in an address on March 21 in which she laid the blame on Parliament. “Do they want to leave the EU with a deal? Do they want to leave without a deal? Or do they not want to leave at all?” she asked, before answering her own question: “So far, Parliament has done everything possible to avoid making a choice.” A backlash from angry MPs quickly followed.

May seemed to be under assault from all sides. On March 23, hundreds of thousands of demonstrators marched in London demanding that another referendum on Brexit be held. “Time’s Up, Theresa” the front page of The Sun newspaper read on March 25, introducing an editorial that advised May to announce that she would leave office as soon as her plan was approved and Britain was out of the EU.. Calls for her resignation multiplied. On March 25 the House of Commons voted 329–302 to temporarily usurp the government’s control of the body’s agenda to allow for “indicative votes” (nonbinding tallies intended to gauge support) on alternatives to May’s plan, with the debate and voting to take place on March 27.

The “indicative votes,” a third rejection of May’s plan, a new deadline, and her resignation

Sixteen alternative proposals to May’s plan were advanced by MPs, of which Speaker of the House John Bercow chose eight to put to a vote. None of the proposals was able to command a majority. A plan to seek to create a “permanent and comprehensive U.K.-wide customs union with the EU” came closest to winning majority support, falling sort by six votes (265–271). The so-called Common Market 2.0 (“Norway plus”) plan, calling for U.K. membership in the European Economic Area (EEA) and the European Free Trade Association (ETFA), failed 283–188. A proposal for another referendum on Brexit came closer, with 268 MPs supporting it and 295 opposing it. The door was left open to holding new votes in the coming week.

Also on March 27, in a closed-door meeting with rank-and-file members of the Conservative Party, May pledged to resign as party leader and prime minister if the House of Commons were to approve her plan. “I am prepared to leave this job earlier than I intended in order to do what is right for our country and our party,” she said, according to government sources. May indicated that she would step down sometime after the May 22 withdrawal date. The promise of her departure garnered support for the plan from several prominent opponents, including Boris Johnson.

In the meantime, Speaker of the House Bercow had invoked a procedural rule dating to 1604 (and last applied in 1920) that prohibited the House of Commons from voting on the same matter more than once during the same sitting of Parliament. As a result, when the House of Commons convened on March 29 to reconsider May’s plan, the vote was limited to one component of the plan: the withdrawal agreement (the terms of the transition period during which the long-term arrangement between the U.K. and EU would be established, including the interim trade relationship between them). Thus, the “political declaration” addressing what both sides expected of their long-term relationship was left off the table. May’s self-sacrificial gambit did win more support for her plan but not enough. It was voted down 344–286, leaving the future of Brexit and that of May hanging precariously.

May responded by asking the EU to extend the deadline for Brexit until June 30. On April 11 the European Council announced that it was granting a “flexible extension” until October 31, before which Britain could still ratify the existing agreement, reconsider its whole Brexit strategy, or revoke Article 50 and cancel Brexit altogether. The next day Nigel Farage, who had played a catalytic role in the original push for Brexit as leader of the United Kingdom Independence Party, announced the formation of the Brexit Party to compete in elections for the European Parliament as advocates for hard Brexit.

Having been unable to win sufficient support from her own party for her Brexit deal, May and the government then entered into negotiations with Labour leaders in an attempt to garner opposition backing for a compromise approach. In the meantime, growing disenchantment among Conservatives led to renewed calls for May to step down and to jockeying for position to replace her. On May 16 the prime minister announced that she would be putting in place a timetable for her resignation in June regardless of the results of the next vote on a withdrawal plan. This development prompted Corbyn to end roughly six weeks of intermittent cross-party negotiations, largely out of fear that agreements reached with May might not be honoured by her successor.

In a last-ditch effort to push her Brexit deal across the finish line, on May 21 the prime minister proposed that a new version of it that included tweaks relating to workers’ rights and environment protections, along with a temporary customs relationship with the EU, be voted on in June. Perhaps most important, the proposal also included a pledge to hold a parliamentary vote on whether to stage another referendum on Brexit. Already mindful that opinion polling was projecting the Brexit Party to be the big winner in the European Parliament elections, May’s cabinet revolted against her latest proposal. Farther out on the limb than she had ever been, May stepped outside of Number 10 Downing Street on May 24 and announced that she would resign as Conservative Party leader on June 7 but would remain as caretaker prime minister until her party completed the steps necessary to choose her successor.

The campaign to replace her began with 10 candidates being put to a vote by the parliamentary party. Subsequent voting winnowed the competitors to two candidates, Boris Johnson and Jeremy Hunt, who then stood in an election in which all of the party’s roughly 160,000 members were eligible to vote. By capturing some 66 percent of that vote, Johnson ascended to the leadership and officially replaced May as prime minister on July 24.