Justin Trudeau has been Canada’s prime minister since November 2015, longer than any other leader of a major western democracy. But a series of political fumbles — including the scathing resignation of his finance minister,

By suspending Parliament and promising to resign, the prime minister bought the Liberals time. But Canada will now face Donald J. Trump with a lame duck in charge.

C anadian Prime Minister Justin Trudeau is stepping down as the leader of the ruling Liberal Party, following months of pressure from partymates to resign amid increasingly poor public approval ratings.