LONDON—British lawmakers this week begin debating Prime Minister Theresa May’s Brexit plan before a critical vote she is widely expected to lose, heightening political and economic uncertainty as Britain’s withdrawal from the European Union nears.
With the U.K.’s exit slated for March 29, the British Parliament appears as divided as ever over Brexit. If lawmakers don’t resolve their differences soon, the country’s economy faces the risk of widespread disruption from a messy and abrupt divorce instead of the smooth withdrawal...