CALGARY, Alberta — This should not have been a competitive election.

When Justin Trudeau won a healthy majority government in 2015, it seemed as if destiny itself had cleared the way for the scrappy scion of former Prime Minister Pierre Trudeau to dominate Canadian politics for years to come. Neither the Conservative Party nor the New Democratic Party nor the Green Party had any leader in the hopper who seemed able to compete with the Kennedy-esque Mr. Trudeau, who scored photo shoots in Vogue and his own comic book cover. He should have been untouchable for an election or two, at least.

And yet on Monday, Mr. Trudeau’s government was reduced to a minority. His party lost the popular vote to the Conservatives. Canada’s electoral map is now disturbingly divided between the Liberal-dominated east of the country, and the Conservative-dominated west. Mr. Trudeau will likely depend on the support of the other parties to keep his hold on power.

What happened to Canada’s progressive idol? The short answer is that Mr. Trudeau came to power when Canadian politics was dominated by issues like deficit spending, electoral reform and whether a local Conservative candidate peed in a cup on television. At the time, he presented a happy contrast to incumbent Prime Minister Stephen Harper, who seemed stodgy, cynical and petty by comparison. Mr. Trudeau’s campaign promised “sunny ways” and at a time when the future looked rosy for Canada, voters responded warmly to the change of tone.

But the world has grown much scarier and more uncertain since the 2015 election. And Mr. Trudeau has done little to convince voters that he is the right man to manage it.