Conservative Party members in British Parliament are voting right now on their faith in Prime Minister Theresa May. Voting — which is done by secret ballot — closes at 3 p.m. ET. We expect to learn the results not too long after that.
If she loses the no-confidence vote she'll be out as the Conservative leader, and she'll likely outline when she will stand down as UK Prime Minister.
How we got here: The vote was triggered after at least 48 Conservative Members of Parliament — that's 15% of them — submitted letters demanding a vote.
What happens now: May needs a majority of Conservative members to stay in power. The magic number is 159. If she gets that many votes, she won't face another challenge for a year.
Here's a handy flowchart of how this process works: