Sources said both sides want a deal, but cautioned there remain disagreements on key issues, including dairy, culture and the Chapter 19 dispute resolution mechanism.
"We continue to work hard", Canadian Foreign Minister Chrystia Freeland told reporters camped outside the talks in Washington.
In a sense, experts say, the easier task for Trudeau to is act on Canadian public opinion on Trump.
President TrumpDonald John TrumpTrump denies calling Sessions "mentally retarded, ' "dumb Southerner" Pressley blasts Trump as 'racist, misogynistic, truly empathy-bankrupt" Capuano falls to Democratic challenger Pressley in Mass. primary MORE and Canadian Prime Minister Justin Trudeau have each staked out their positions, raising the temperature of the negotiations, which restarted last week after a five-week break.
The Trump administration last week reached a tentative deal with Mexico that updates the quarter-century-old NAFTA by incorporating labor and environmental chapters as well as intellectual property protections that were not part of the original pact.
Talks with Canada aimed at bringing the top U.S. trading partner into the tentative deal struck with Mexico broke off Friday without success, but the parties agreed to continue talks this week. Dispute settlement, Canada's cultural exemption and access to Canada's dairy market continue to be obstacles to a deal.
"If we don't make a fair deal for the USA after decades of abuse, Canada will be out", he tweeted.
At Trump's behest, the three NAFTA countries have been negotiating for more than a year to revamp the trilateral agreement that has been integral to the continent's economy for more than two decades.
Lighthizer laid out his concerns about the issue in his March report to Trump on the trade barriers faced by the United States.
But Trudeau is also digging in and vowing that Canada won't be pressured into a deal.
Speaking to dozens of supporters at a posh banquet hall, he said he believes his party won the 2015 election by putting out a message of positivity.
The tentative deal struck with Mexico calls for a horizon of 16 years for the new terms, with provisions for a review of the revised pact every six years. "But I think certainly we were always intending to take as long as it was going to take", said a government source, who declined to be identified given the sensitivity of the situation.
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Wednesday's news of Thomas reporting to his current team might well lead to both sides considering it a stalemate. Obviously, the All-Pro safety wasn't happy, but he'll be back on the field for Seattle in Week 1.
The text of the new trade deal still remains largely under wraps.
Chicago Tribune: "Car prices projected to increase under Trump trade agreement with Mexico" - "New auto prices will rise, along with demand for used cars, as a result of President Donald Trump 's tentative trade agreement with Mexico".
The Canadian dollar initially gained slightly, touching C$1.3166 to the US dollar, or 75.95 USA cents, before settling back to C$1.3185, or 75.84 USA cents.
Canadian and USA negotiators could not reach a deal to meet Trump's deadline last Friday. "As the Trump administration has been dealing with trade around the country, what I've been doing is, as it impacts Florida businesses, I've been talking to Bob Lighthizer, who's the federal trade representative, and letting him know the importance of free trade and how it's impacting Florida businesses", Scott said.
"We will not sign a deal that is bad for Canadians, and quiet frankly, not having a Chapter 19 to ensure the rules are followed would be bad for Canadians", he said. Canadian officials have repeatedly said that demand is a non-starter for Canada.
But other issues have yet to be worked out, including Canada's cultural exemption in NAFTA. "That would not be good for Canada, it would not be good for our identity, it would not be good for our sovereignty".
Polls showed that Canadians cheered when their prime minister announced this summer that Canada would not be pushed around by President Trump.
In the US, businesses, farmers, unions and Congress insistent that there must be a three-nation agreement. The president also said the USA would be fine if a deal can't be reached with its northern neighbour.
One thing is clear: Congress could help determine who has leverage in this week's bilateral talks.
USA senators Marco Rubio and Bill Nelson quickly warned that the agreement needs to better protect the state's agricultural industry, and state Agricultural Commissioner Adam Putnam said Trump's newly negotiated agreement "wasn't quite the deal we hoped it would be" in Florida.
"The president needs to take a look at the Constitution - it gives Congress authority over trade". As the process grinds on, some in Washington insist Trump can not pull out of NAFTA without the approval of Congress.
"The president doesn't have a deal, he doesn't have a plan, and he doesn't even have the power to follow through on his empty threats".