Canada’s trade relationship with the United States could be in trouble, regardless of who wins the U.S. presidential election in November, according to former Quebec Premier Jean Charest. 

"If there is protectionism in the United States, even when Canada is not targeted, we are more often than not collateral damage," Charest told BNN in an interview.

Charest, currently a partner in the Montreal office of law firm McCarthy Tétrault, played a key role in the creation of the Canada and European Union Comprehensive Economic and Trade Agreement (CETA), which is currently awaiting ratification.

"It's a key moment for Canada to get this deal done, post-Brexit," Charest said. The CETA deal would give Canada access to a market of 500 million people, and lessen the country’s dependence on trade with the U.S.

"We do know from what is happening now politically in the United States that the day after the election, things are not going to be better -- whether it's Madame Clinton or whether it's Mr. Trump -- it's not going to be better."

According to the Government of Canada, total merchandise trade between Canada and the United States doubled between 1993 (when the North American Free Trade Agreement was signed into law) and 2015, with 78 per cent of Canada’s total merchandise exports destined for NAFTA partners last year.

Since winning the Republican presidential nomination, Donald Trump has continued to voice an anti-NAFTA view. "Mr. Trump would be the worst scenario,” said Charest. “He's already stated that he is going to cancel NAFTA, which would be, frankly, a disaster for the United States, but also bad for Canada and Mexico."

On Tuesday, United Auto Workers President Dennis Williams said Hillary Clinton, who this week secured the Democratic Party’s nomination for the White House, told him she is open to renegotiating NAFTA if elected President.

"It's difficult to see that even with a new Democratic Clinton administration, how it would better than it is now,” said Charest.  “I think we are going to see the Americans on the defensive and in isolationist mode for the foreseeable future."