May\'s Grip on Power Weakens as Lawmakers Quit Over Brexit

Theresa May’s Grip on Power Weakens as Three Lawmakers Quit Over Brexit

Lawmakers leave the U.K.’s governing party to join former opposition rivals in new Independent Group

With U.K. lawmakers rejecting Theresa May’s Brexit deal, WSJ’s Stephen Fidler explores what options remain available to the prime minister before the country is scheduled to leave the EU on March 29.

LONDON—Three lawmakers quit British Prime Minister Theresa May’s Conservative Party on Wednesday over Brexit, which further adds to the precariousness of her grip on power and underlines how the decision to leave the European Union is reshaping British politics.

The defection to a newly formed group espousing the political middle ground narrows Mrs. May’s already razor-thin working majority and reinforces the struggle she will face to push her Brexit deal through Parliament before the U.K.’s scheduled EU departure date of...