From all sides of the political spectrum, there was opposition to the Brexit deal British Prime Minister Theresa May brokered with European leaders.
Parliament was expected to reject it in a vote on Tuesday, but May pulled the poll and returned to Europe seeking amendments.
Forty-eight Conservatives have now managed to raise a vote of no confidence that will take place on Wednesday between 18:00 and 20:00 GMT. The result comes soon after.
If she loses, she must resign. She may stay on as interim prime minister until the Conservatives choose another leader - which could take six weeks.
