Several Democrats questioned whether the Trump administration has the legal authority to proceed with a Mexico-only deal when prior notifications under the "fast-track" trade negotiating authority law were for a trilateral deal including both Mexico and Canada.
The two nations are now working to avoid a fight that could jeopardize $500 billion in annual trade, according to the tweet.
A second Ottawa source said the two sides were still trying to resolve disagreements over a dispute resolution mechanism that Canada says is vital and the United States wants to scrap.
Officials told CBC News that the postponement of her speech was due to the trade negotiations, which sources say intensified this week in the face of Monday's USA congressional deadline.
But on Thursday the prime minister disputed Trump's statement, insisting Canada made no such request. He has moved quickly to finalize a trade deal with Mexico that makes no mention of Canada, shattering the notion of the "three amigos" pact that once governed free trade across the continent. According to The Wall Street Journal, the dispute between USA and Canada hinges on agricultural and media protection policies, as well as the installation of a system that would allow any of the three countries in the agreement to challenge tariffs imposed by one of the others.
The president added new pressure to trade talks Wednesday when he took aim at Trudeau and the Canadians, saying he won't make the deal they're seeking, that he doesn't like Canada's representative and that he might apply auto tariffs to the northern nation.
Lopez Obrador said there were no final deadlines in the negotiation.
Trump's officials have argued that they need to publish the text by Sunday in order to let the outgoing Mexican president, Enrique Pena Nieto, sign the deal by his last full day in office, November 30, and avoid the possibility that Lopez Obrador will demand changes. "And that's where things stand".
United States and Canadian negotiators were expected to work all weekend via secure video link, The Globe and Mail newspaper reported Saturday, citing sources in Prime Minister Justin Trudeau's administration and on the U.S. industry side.
"Frankly, we're thinking about just taxing cars coming in from Canada", Mr. Trump said at a press conference earlier this week.
The office of Canadian Foreign Minister Chrystia Freeland did not respond to requests for comment.
Speaking as he presented the Mexican Senate with the current US-Mexican agreement to update NAFTA - which does not include Canada, the third member of the original deal - Economy Minister Ildefonso Guajardo said Washington and Ottawa were making a 'very serious, ' last-ditch attempt to bridge their differences.
USA business groups oppose turning NAFTA into a bilateral deal because the three nations' economies have become closely intertwined since the original pact came into force in 1994.
He said there was a counter-proposal Friday from the United States.
So-called Chapter 19 dispute panels, which the US wants to eliminate from Nafta and which Canada wants to preserveAn exemption for cultural sectors which Canada wants to preserveThe use of Section 232 investigations to apply tariffs to steel, aluminum, and potentially autos.
But a Mexican source close to the talks said the United States had in turn agreed to drop a demand for tariffs to protect US seasonal produce growers.
Details are also expected on an automotive side-letter that preserves the Trump administration's ability to impose global national security tariffs on imports of autos and auto parts, granting Mexico a quota for tariff-free exports to the United States that allows some expansion of production.
NAFTA talks will continue throughout the weekend, and there are now no plans for Freeland to head back to Washington, D.C., in the immediate future. "If not, then the process gets more complicated, but it's also possible to come in ... some days after", Perez Jacome said.