Answer:
They worry that American jobs could go to Mexico.
Explanation:
Nafta is an economic bloc created in 1989 and made official in 1994. It is composed of the United States, Canada and Mexico, and also Chile as an associate member.
For the United States and Canada, NAFTA serves as an important trade and economic agreement to expand its consumer markets, since in that treaty the main objective is the realization of trade agreements. Thus, their technological products find it easier to migrate, mainly towards Mexico and its broad consumer market.
Another interest, on the part of Americans and Canadians, is the facility that Nafta offers for the expansion of its multinationals in Mexico, where they find cheap and abundant labor, as well as cheap and available raw materials. That is why some Americans fear that the available jobs will be filled by the Mexicans leaving the Americans unemployed.