Front-runner Mark Carney and underdog Chrystia Freeland, both established, centrist policymakers, are vying to succeed Justin Trudeau amid grave threats to Canada from the United States.

U.S. President Donald Trump, who has imposed tariffs on Canadian goods and threatened to make Canada the 51st state, has loomed large over the contest.

Canada's ruling Liberal Party is choosing a new leader on Sunday to replace Prime Minister Justin Trudeau, who said in January he was stepping down after growing dissatisfaction over his performance.