LONDON—A British minister resigned unexpectedly Tuesday citing the government’s approach to Brexit, hours ahead of a showdown in Parliament over whether lawmakers can wrest some control from the government of the deal to leave the European Union.
The votes in the House of Commons, the elected chamber, could influence negotiations over the future relationship between the EU and the U.K. after Brexit. The results could also deliver a further blow to Prime Minister Theresa May’s authority, which was severely damaged when she...