When Prime Minister Mark Carney appeared last Sunday on Quebec’s most popular talk show, “Tout le Monde en Parle,” the most consequential question may not have been about President Trump or tariffs. Instead, it was probably when the host asked him what he “knew or liked about” Canada’s French-speaking province.

“A singer? A city? A feature? A cheese? Anything?” the host, Guy Lepage, suggested, in French, as Mr. Carney laughed but gave no clear answer.

Winning over voters in Quebec has usually, in great part, meant winning hearts by speaking French, grasping the province’s history and appreciating its culture. That was never going to be easy for Mr. Carney, a political novice whose appeals to Québécois voters have been marked by his faltering French and a series of gaffes that have raised doubts about his basic knowledge of Quebec, the country’s second-most-populous province.

Until a few months ago, the Bloc Québécois — a party that runs candidates for the federal Parliament in Quebec but that supports independence for the province — appeared headed for a big victory that would have considerably hurt Mr. Carney’s chances of winning the April 28 federal election. But Mr. Carney and his Liberal Party now have a huge lead in the polls in Quebec.

The abrupt reversal is another sign of how Mr. Trump’s tariffs and aggressive threats of annexation have upended Canada’s elections. Most Canadians regard Mr. Carney, a former head of the Bank of Canada and the Bank of England who has never before run for office, as the most capable candidate to deal with the American president, polls show. Even many hardcore supporters of the Bloc Québécois are now considering Mr. Carney and are cutting him some slack for his lack of connection to Quebec.