A Canadian delegation heads into trade talks in Washington on Wednesday, and is determined not to back down on key issues despite threats from President Trump to retaliate.
Trump arranged a side deal last week with Mexico and has even mentioned excluding Canada from the pact altogether.
Trump is also ready to slap auto tariffs on Canada, according to Reuters.
The president says the original NAFTA pact caused hundreds of thousands of manufacturing jobs to leave the United States.
The Trump administration wants to scrap a dispute-resolution mechanism that Canadian Prime Minister Justin Trudeau says is crucial.
The two sides, which failed to settle their differences last week, are also arguing over U.S. demands for more access to Canada's closed dairy market.
The process has already gone through a number of deadlines since August 2017.
Some in Washington insist Trump cannot pull out of NAFTA without the approval of Congress.