Mrs. May said that she was honored to serve the country as its “second female prime minister, but certainly not the last,” and that the role had been the honor of her life.

Catch up: The current deadline for Britain to leave the European Union is effectively Oct. 31, after having been previously postponed. Read our guide to the Brexit process.

Go deeper: Mrs. May was initially seen as a “safe pair of hands” to deliver Brexit, but she ultimately failed to convey any convincing vision of a future for Britain outside the European Union.

What’s next: The Conservative Party chairman said today that a new leader would be in place before Parliament’s summer break, which usually begins in late July. Here’s a look at the likely contenders, including the former foreign secretary, Boris Johnson; the former Brexit secretary, Dominic Raab; and Andrea Leadsom, who left her cabinet post as leader of the House of Commons this week.