LONDON (AP) — On a day of humiliating setbacks, British Prime Minister Boris Johnson suffered a major defeat in Parliament on Tuesday night as rebellious lawmakers voted to seize control of the Brexit agenda, prompting the embattled leader to say he would call for a new general election.

The 328 to 301 vote, made possible by 21 fellow Conservatives who turned their back on Johnson's pleas and face ejection from the party, cleared the way for his opponents to introduce a bill Wednesday that would seek to prevent Britain from leaving the European Union without a deal Oct. 31. It was a momentous...