Political careers often end in failure — a cliché that exists because it too often happens to be true. Justin Trudeau, one of the world’s great progressive leaders, may be heading toward that moment. In a recent interview he acknowledged that every day he considers leaving his “crazy job” as Canada’s prime minister. Increasingly, the question is not if he will leave but how soon and how deep his failure will be when he goes.

At stake is something that matters more than one politician’s career: Canada’s contemporary liberal and multicultural society, which just happens to be the legacy of the prime minister’s father and predecessor, Pierre Trudeau. When you fly into Montreal, you land in Trudeau airport, and that’s because of Pierre, not Justin.

The threat to that liberal tradition is not all Justin Trudeau’s fault, of course. The right-wing tide overwhelming global politics has come late but with pent-up vigor to Canada. For several years now, polls have shown Mr. Trudeau’s Liberals at lows from which no Canadian political party has ever recovered in elections. In a recent by-election, in a key suburban district of the Greater Toronto Area, the Conservative Party beat the Liberals by a lopsided 57 percent to 22 percent, a swing of nine percentage points to the Conservatives.

But polls and by-elections can be poor predictors of election viability. A better indicator is the flummoxed figure of Mr. Trudeau himself, who seems increasingly out of touch in the new world of division and extremism.

Part of Mr. Trudeau’s problem is simple exhaustion, both his own and Canadian voters’. He has been in government for almost eight and a half years. During that time, he has been one of the most effective progressive leaders in the world. His government cut Canada’s child poverty in half. He legalized marijuana, ending roughly 100 years of nonsense. He made large strides in reconciliation with Indigenous Canadians. He renegotiated NAFTA with a lunatic American president. He handled Covid better than most. You don’t have to squint too hard to recognize that he is one of the most competent and transformative prime ministers this country has ever produced.

But an era has passed since the start of that halcyon time, when Mr. Trudeau stood in front of his first cabinet and, when asked why it was half female, answered, “Because it’s 2015.” Now a new generation has emerged, for which the liberal technocratic order his government represents has failed to offer a path to a stable, prosperous future and the identity politics he once embodied have withered into vacuous schism. The growing anti-Liberal Party sentiment of young people is the biggest threat to his electability.