Trump the dealmaker must learn that nationalism cuts both ways or risk wrecking his presidency

President Donald Trump is nothing if not strong-willed, and he’s the leader of the mightiest nation on earth — but there’s one power even Trump can’t afford to discount.It’s the power of nationalism and national pride, which Trump himself harnessed to win two terms in the White House.But the same force that helped make him president will wreck his presidency if he fails to take it seriously enough in his foreign policy.Trump is a consummate dealmaker, and bargaining with friends and foes alike depends on appealing to their self-interests.But self-interest isn’t always a stronger motive than self-respect where other nations are concerned.The president could get away with needling then-Prime Minister Justin Trudeau, referring to him as the “governor” of Canada.Yet he can’t tease Canada into becoming America’s 51st state, and outright economic warfare — if his threatened tariffs ever come into full effect — won’t suffice, either.Trump demolished Trudeau’s premiership, but the American president is actually strengthening Trudeau’s Liberal party, whose new leader, Mark Carney, has called snap elections to capitalize on the opportunity Trump has created for him.Canadians were dismayed by Trudeau’s Biden-like performance and ready to dump the Liberals in favor of the Conservative Party and its leader, Pierre Poilievre.The Conservatives had a wide lead in polls — until Trump declared a trade war and started talking about taking over Canada.Canadians know full well how dependent they are on American trade, but they also feel there’s more than money at stake here: Trump has called into question Canada’s very right to exist as an independent nation, and that’s awakened Canadians’ long-dormant nationalism.Carney, as leader of the party in power in Ottawa, gets to play hero by promising to stand up to the foreign bully, and now polls show the Liberals tied with the Conservatives — who have been quick to assert their own patriotic zeal ...