From the WSJ:
As the Democratic contest continues, it is becoming a race to the bottom on protectionism. Perhaps the best trade demagogue will win, but someone should point out that the last President who tried to govern as a protectionist was Herbert Hoover. It didn’t turn out so well.
Obama gave the heads up to Canada that he’s running for office, so just disregard what they may here
Obama’s Sotto Voce To Canadians: I’m Demagoguing On NAFTA
Obama staffer gave warning of NAFTA rhetoric
Re-negotiating NAFTA: Some Reaction from Canada
Emerson hints oil would be back on table if U.S. reopens NAFTA
Canada’s Emerson Says Nafta Trade Accord Is at Risk
I hate to break it to everyone but Canada has always had much more stringent protectionist laws than we do.