"Specifically, we will seek clarity on how the agreement addresses the existing tariffs on Canadian steel and aluminium, as well as how it will ensure that tariffs and quotas upon Canada's auto sector exports will be avoided", Beatty said in a statement.
Ambassador David McNaughton said Sunday evening in Ottawa there are a couple of tough issues left to resolve.
President Trump and Canadian Prime Minister Justin Trudeau shake hands during a meeting in the Oval Office in February.
The trade impasse was overcome after both parties made some concessions, with Canada agreeing to grant USA farmers greater access to its dairy market and limit its automotive exports to the US.
The pending deal followed 11th-hour. He blames the treaty for the loss of American manufacturing jobs and has repeatedly threatened to abandon the trade past signed in 1994, during the Clinton administration. The president said he had rejected a meeting with Trudeau because of Canada's high tariffs, though Trudeau's office said no meeting had ever been requested.
Two Ottawa sources directly familiar with the talks said a deal could be very close but stressed some challenging matters had yet to be solved.
It is unclear at this time whether the new NAFTA includes a sunset clause.
However, a frosty relationship between Trump and Trudeau has made things more complicated recently.
Next, the dispute settlement mechanism is going to remain in place, which is something that Canada pushed for, she pointed out.
Tempers flared this week on both sides as the end-of-month deadline approached.
A bulk of Canada's efforts this weekend have been focused on securing an exemption to the Section 232 tariffs - especially dealing with autos - which allow President Donald Trump to slap duties on foreign products in the name of national security, a source with direct knowledge of the talks confirmed.
Because the old agreement was cemented by Congress, and was not a treaty, Mr. Trump would still have to get Congress on board and, under US law, Mr. Trump will have to made the agreement public two months before he can sign it.
Speaking at a political rally in Wheeling, West Virginia on Saturday night, Trump told supporters: "We´ll see what happens with Canada, if they come along".
Mexico's new president-elect, however, said in an interview Friday that he has agreed to push the American side to make a deal with Canada.
USMCA doesn't trip off the tongue like NAFTA, but that didn't stop Justin Trudeau's cabinet signing the deal off shortly before midnight in Washington, to avoid trade relations with the USA being poisoned.
The official also said it exempts tariffs on 2.6 million cars and on diary it preserves supply management in Canada, the AP reported. That is more than the 2 million units now exported.
The White House and Mexico announced on September 28 that they would release the full text of the bilateral deal that the two countries reached in August.
The new deal must now go to Congress for approval, with a vote not expected until next year, after midterm elections.
Under U.S. trade law, an agreement must be published for 60 days before it can be signed by leaders of any of the participant countries, putting negotiators on the clock to reach a deal that can be signed by November 30.
Among the tough issues that needed to be hashed out between Ottawa and Washington were access to Canada's dairy sector, tariffs and a dispute resolution mechanism that the USA wanted to scrap.