Canadians will head to the polls in October and Liberal Prime Minister Justin Trudeau has been looking vulnerable. If he loses, it would be a remarkable fall from grace for the 47-year-old son of former Prime Minister Pierre Trudeau. Not long ago his future seemed secure.

Mr. Trudeau swept into office in 2015, ending a decade of Conservative government. The Canadian media loved the telegenic and vibrant new leader then; today pundits across the political spectrum question his leadership, temperament and policy knowledge.

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