Chrystia Freeland blew up the career of her top political ally, Justin Trudeau. Now, she is taking on an old friend, the former central banker Mark Carney.

Chrystia Freeland, the former deputy prime minister, sought to distance herself from Mr. Trudeau in a public letter criticizing him for “costly political gimmicks.”

Canada's ruling Liberal Party is looking for a new leader to replace Prime Minister Justin Trudeau, who announced on Jan. 6 he intended to step down. The Liberal Party will pick a new chief on March 9.