In their backgrounds and political styles, Canadian election front-runners Mark Carney and Pierre Poilievre are a study in contrasts.

Whatever the case, one thing was clear: Mr. Trump is not giving up on his obsession with Canada, and the new government that emerges from Monday’s vote will need to deal with a leader intent on both hurting Canada’s economy with tariffs, and coveting its vast resources.

Canada’s Pierre Poilievre seemed to be cruising toward victory in the next election. His Conservative Party was polling around 20 percentage points ahead of Justin Trudeau’s Liberals because of growing voter frustration around political scandals and rising housing costs.