U.S. Trade Representative Robert Lighthizer acknowledged that the talks to renegotiate the North American Free Trade agreement are making little headway, following the end of the fifth round of negotiations.

Canada and Mexico have been resisting U.S. demands for a radical rewrite of the 1993 deal. The situation has heightened concern among business groups that President Trump will follow through with his earlier threats to pull the U.S. out of the deal.

Following Tuesday's conclusion of the fifth round of talks, Lighthizer said that there had been some progress on the administration's goals but that there had been no change on the big issues. "I remain concerned about the lack of headway. Thus far, we have seen no evidence that Canada or Mexico are willing to seriously engage on provisions that will lead to a rebalanced agreement. Absent rebalancing, we will not reach a satisfactory result," he said.

Lighthizer added that there was still time. "A rebalanced, updated NAFTA will promote greater prosperity for American workers, farmers, ranchers and businesses and strengthen the North American region as a whole. Our teams will be meeting again next month in Washington. I hope our partners will come to the table in a serious way so we can see meaningful progress before the end of the year."

The NAFTA renegotiations have been strained. Canadian and Mexican officials rejected U.S. demands to change the rules for determining when a product can be labeled as "made in America" or "made in the U.S.A.," arguing that the changes would damage the auto industry, whose supply chain is spread throughout the continent, according to an official with knowledge of the talks. The administration also is pushing to add an expiration clause to NAFTA as well as to allow countries to opt out of its investment dispute settlement system, changes the trading partners also object to.

"Significant differences remain on some key areas. ... These are proposals we simply cannot agree to," Canadian Foreign Minister Chrystia Freeland told reporters in Ottawa Tuesday.