Ford Motor Co., the largest producer of cars and trucks in the U.S., remains concerned about major modifications to the North American Free Trade Agreement, even after President Donald Trump’s negotiators were said to have softened demands.

After having pushed for 85 percent of all vehicle content to be sourced from the U.S., Canada and Mexico, the Trump administration’s latest proposal would only apply that requirement to major components such as transmissions and engines, according to three people familiar with the talks. While that’s less arduous than earlier U.S. demands, automakers would still be hard-pressed to hit the 85 percent threshold on critical parts.

“We appreciate U.S. negotiators’ goal to support American jobs,” Christin Baker, a Ford spokeswoman, said in an email. “However, there is a concern that significant changes to the rules of origin would not achieve that shared goal. We look forward to seeing the official details, and we continue to urge negotiators to include enforceable rules prohibiting currency manipulation in a revised Nafta.”