U.S. and Mexican senior officials are meeting in Washington this week in an effort to break an impasse over auto-production rules in an updated Nafta, according to two people familiar with the negotiations.

Mexican Deputy Economy Minister for Trade Juan Carlos Baker is meeting with Deputy U.S. Trade Representative C.J. Mahoney and other USTR officials to review Mexico’s automotive proposal, according to the people, who asked not to be identified because the talks are private. The issue of autos has been a key sticking point in nine months of talks between the U.S., Mexico and Canada to revise the 24-year-old North American Free Trade Agreement.

The push comes as the Trump administration races against the clock to reach a Nafta deal that could be approved by Congress before midterm elections in November. If that doesn’t happen, negotiations could run into 2019. President Donald Trump has threatened to withdraw from the pact if he doesn’t get a deal favorable to the U.S.

The press office of the U.S. Trade Representative didn’t immediately return an email seeking comment, while the press office of Mexico’s economy ministry declined to comment.

‘Very Difficult’

Trump said Wednesday that renegotiating Nafta “is very difficult” but autoworkers “are going to be extremely happy with the results.”

“Mexico has been very difficult to deal with, Canada has been very difficult to deal with. They have been taking advantage of the United States for a long time. I am not happy with their requests but I will tell you in the end we win, we will win and we’ll win big,” he told reporters.

Mexico has clashed with the U.S. over the Trump administration’s proposal to require that 40 percent of a car’s value be made with high-wage labor. Mexico has countered with an offer that included as one option a requirement that 20 percent of a car be made with high-wage labor, according to people familiar with the discussions.

Mexico’s peso extended gains, strengthening more than 1 percent to 19.5632 per dollar at 2:30 p.m. New York time.

Canadian Foreign Minister Chrystia Freeland said she hadn’t heard Trump’s comments about being difficult, but that trade between the two nations is mutually beneficial and balanced. Auto rules of origin have been a primary focus of recent talks and there’s been progress, she said, reiterating her view that Nafta can be renewed so that every nation wins.

“The government of Canada, the Prime Minister and I personally will always be absolutely resolute in our defense of the Canadian national interest, all the time, and very particularly during these Nafta negotiations,” she told reporters in Ottawa.