Larry Kudlow, Trump's senior economic adviser, said he and Trump hadn't spoken in detail about the president's thinking.
Lawmakers disagree about whether the president has the ability to withdraw unilaterally from NAFTA, but a number of lawmakers insist he doesn't, and some Democrats scoffed at the threat.
Congress should work quickly to ratify the newly signed U.S. -Mexico-Canada Agreement (USMCA) to provide market certainty and stimulate investment in the economy, said Association of American Railroads President and Chief Executive Officer Edward Hamberger in a press release.
The deal signed Friday already included some tweaks from the one struck two months earlier, changes apparently aimed at wooing congressional support.
Even as he suggested he would make such a drastic move, he played down its potential impact, adding that he would have no problem reverting to a "pre-Nafta" environment. Millions of products arrive in USA ports annually and are then transported by trucks. Trump has repeatedly criticized NAFTA, calling it "the worst trade deal in history".
"I'm in discussions with a variety of Democratic leaders on those points and they will be very much involved in the process moving forward and will have a strong influence on how we put things together, because I want them not only to vote for it, I want them to be happy".
The new deal also requires legislative approval in Canada and Mexico.More news: George H.W. Bush’s funeral and memorial services plan
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"As it stands, this agreement has not earned the support of America's working families", he said in a statement.
What has Congress said about this?
The leaders of the three countries agreed on a deal in principle to replace NAFTA, which governs more than $1.2 trillion of mutual trade, after acrimonious negotiations concluded on September 30.
The U.S. can tuck some changes into the trade deal's implementing legislation and request that Mexico and Canada go along with it.
Trump had vowed to revamp NAFTA during his 2016 presidential election campaign. "I'm committed to strengthening this vital relationship, and fighting for necessary protections for worker's rights and environmental standards that will benefit New Mexico". The commission has up to 105 days, or by mid-March to complete a report.
Rubio's office said Monday that the senator had asked Lightizer to look into additional trade actions to protect Florida growers, and that Lighthizer had committed to requesting a fact-finding investigation and taking corrective action.