The opponents of NAFTA include labor and environmental groups, among others. Labor groups voiced their fears of wage and benefit reductions that would be asked for in the name of competitiveness, as well as their fears of complete job displacement. They foresaw American companies moving to Mexico to reap the ultra cheap labor and lax environmental laws. Environmentalists envisioned more severe environmental degradation in Mexico where environmental laws are lax and often unenforced. They also predicted that there would be a weakening of America's present environmental laws in the name of staying competitive with Mexico. Critics include labor leaders such as John Sweeney, president of the AFL-CIO, and some political figures such as Rep. Richard Gephardt, House Minority leader. The Sierra Club, an environmental group, has been a strong critic of NAFTA.
The proponents of NAFTA include most economists, multinational corporations in general, and several key political figures, like President Clinton. Economists predicted the gains their models indicated, while multinational corporations were attracted to the expected bottom line gains.