The Trump administration has drafted an executive order that would withdraw the US from the North American Free Trade Agreement (Nafta), US media say.
It is unclear whether President Donald Trump will follow through and strike down the deal, which eliminated tariffs between the US, Mexico and Canada.
In the election he vowed to withdraw from the 23-year-old pact, calling it a US job killer.
He pulled the US out of the Trans-Pacific Partnership (TPP) in January.
According to Politico, two White House officials said the Nafta draft order could be unveiled this week or early next week.
It is not clear whether the administration is simply floating the proposal as a hardball negotiating tactic, however.
The plan comes days after the US imposed a new tariff on softwood lumber coming from Canada.
Mr Trump also called a new Canadian tariff regime affecting US dairy products a "disgrace".
On Tuesday, the US lost a trade battle with the other Nafta signatory.
The World Trade Organization ruled that Mexico could impose more than $160m (£125m) annually in sanctions against the US on commerce in tuna, capping a dispute dating to 2008.