People have always wondered what it is about now former Canadian Prime Minister Justin Trudeau that Donald Trump just cannot stand. His politics aren't demonstrably different from any other center-left leader Trump has dealt with around the world and the U.

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, a political novice, will take over at a tumultuous time in Canada, which is in the midst of a trade war with longtime ally the United States and must hold a general election soon.