Traditionally, the role of liaison between the White House and Congress would be served by the U.S. Trade Representative. Trump nominated Robert Lighthizer for the post, but there has yet to be a committee hearing scheduled.
Trump previously said trade policy would be led by Commerce Secretary Wilbur Ross and Peter Navarro, who helms a newly created trade council, but only the office of the USTR "has the resources to actually do the negotiation," according to Jeff Schott, senior fellow at the Peterson Institute for International Economics.
Formal negotiations with Canadaand Mexicocan't happen until after the U.S. finishes its deliberations with Congress, despite Mexico on February 1 opening its own 90-day window to consult with its Senate and businesses. That process, Schott says, "is to conduct contingency plans depending on what the U.S. does."
Secretary of State Rex Tillerson and Secretary of Homeland Security John Kelly will visit Mexico City on February 22 and 23, according to the.
Trump could pull the U.S. out of NAFTA without Congressional approval, according to Oxford Economics, as he did by executive order his first week in office for the U.S. involvement in the Trans-Pacific Partnership. But that could be subject to legal challenge.
At a Florida rally on Feb. 18, Trump called that 12-nation deal with nations in Asia and Latin America a "job-killing disaster" and pointed to his commitment to undo trade deals.
Withdrawing from TPP, however, was much simpler: It had not yet been passed by Congress.
NAFTA, on the other hand, has been in practice for more than two decades, which means a hasty exit could cause chaos for businesses.
—CNBC's Stephanie Dhue contributed to this report