U.S. Trade Representative Robert Lighthizer is leading the push as part of President Donald Trump’s “Buy American, Hire American” initiative promised during the 2016 campaign.

The administration wants to limit the number of eligible professions and decrease the number of visa renewals of Treaty NAFTA , or TN, visas as the countries renegotiate the 1994 trade deal. Trump, who has forced the renegotiation, has threatened to scrap it unless it addresses the U.S. trade deficit with Mexico.

“At the negotiating table, the U.S. statements have been basically, ‘Look, we want to scale this back, we don’t want to agree to expand it (visas),’” said Eric Miller, a trade consultant who has worked for the Canadian government and continues to advise them on the negotiations.