The next prime minister and party leader, a former governor of the central banks of Canada and England, will have to deal with the tense relationship with the US

Frontrunners include Chrystia Freeland and Mark Carney, who are making the case they can guide Canada through domestic and international issues. At the top of the list: mounting trade tensions with the United States.

Carney vowed Sunday to “keep our tariffs on until the Americans show us respect” in a message to U.S. President Donald Trump.