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.

After months of speculation about his future, former Bank of Canada governor Mark Carney launched his campaign to replace Justin Trudeau as Liberal leader on Thursday with a promise to build the fastest-growing economy in the G7 if he's elected.

Former Bank of Canada governor Mark Carney announced on Thursday that he was running to replace Prime Minister Justin Trudeau as leader of the ruling Liberal Party, saying he wanted to focus on the struggling economy.