Some House Democrats say they want more attention paid to union workers and environmental protection, and could stall the plan from moving through the chamber.
According to reporting by NPR, the president has said he'll force lawmakers to choose between new NAFTA or no NAFTA.
"Congress will have a choice of the USMCA or pre-NAFTA," Trump said.
Republican Sen. Chuck Grassley says it's within the president's power to force lawmakers' hand.
“[If] the president says, which he can under the existing NAFTA agreement, 'We're just going to pull out of it!' It seems to me it puts big pressure on Democrats to go along with what the president’s negotiated. Because surely no Democrat wants to pull out of NAFTA and go back to the high tariffs we had and the impediments we had to trade, pre-NAFTA,” Grassley said.
Grassley says there are benefits to the deal, including incentive car manufacturers to use more North American-produced components, and setting a $16 an hour minimum wage for certain auto workers.
"I think on the economic issues, Democrats should not have any problems with it," Grassley said.
But Grassley has said he thinks the president has too much power over trade negotiations, and Congress should take some of it back.