Intense negotiations over the past week among U.S. Democrats, the administration of Republican U.S. President Donald Trump, and Mexico produced more stringent rules on labor rights aimed at reducing Mexico’s low-wage advantage.

However, an annex for the implementation of the treaty that was presented on Friday in the U.S. House of Representatives proposes the designation of up to five U.S. experts who would monitor compliance with local labor reform in Mexico.

“This provision, the result of political decisions by Congress and the Administration in the United States, was not, for obvious reasons, consulted with Mexico,” Seade wrote in the letter. “And, of course, we disagree.”