Donald Trump's return to the White House next year could bring economic pain and difficult decisions for Canada's Liberal Prime Minister Justin Trudeau, once branded a "far left lunatic" by the Republican.

While Canadian lawmakers are publicly sanguine about the incoming U.S. administration, several experts say that Canada faces significant challenges.

Justin Trudeau, the Canadian Prime Minister, was quick to congratulate President-elect Donald Trump on his election victory. But there is no doubt their relationship has been rocky and there are challenges on the horizon.

On Wednesday evening, Canadian Prime Minister Justin Trudeau held a phone conversation with Donald Trump. He congratulated the elected US president on his victory, according to the Associated Press and CNN.