In a 60-minute interview in September 2015, presidential candidate Donald Trump described NAFTA as “the worst trade deal ever approved in the United States”[121] and said that if elected, “he would either renegotiate or we would break it.” [122] [123] Juan Pablo Castaen [es], chairman of the trade group Consejo Coordinador Empresarial, expressed concern about the renegotiations and the desire to focus on the automotive industry. [124] A number of trade experts have stated that abandoning NAFTA would have a number of unintended consequences for the United States, including limited access to its key export markets, lower economic growth and higher prices for gasoline, cars, fruits and vegetables. [125] Members of the Mexican private initiative noted that many laws needed to be adapted by the U.S. Congress to eliminate NAFTA. Finally, this would give rise to complaints from the World Trade Organization. [124] The Washington Post found that a review of academic literature by the Congress Research Service concluded that “the overall net effect of NAFTA on the U.S. economy appears to be relatively modest, mainly because trade with Canada and Mexico accounts for a small percentage of U.S. GDP.” [63] Additional ancillary agreements have been reached to allay concerns about the potential impact of the treaty on the labour market and the environment. Critics feared that U.S. and Canadian companies in Mexico would have generally low wages, which would lead to a shift of production to Mexico and a rapid reduction in manufacturing employment in the United States and Canada. Meanwhile, environmentalists were concerned about the potentially catastrophic effects of rapid industrialization in Mexico, which does not have experience in implementing and enforcing environmental legislation. Possible environmental problems were raised in the North American Environmental Cooperation Agreement (NAAEC), which established the Commission for Environmental Cooperation (CEC) in 1994.

A 2014 study on the impact of NAFTA on U.S. trade employment and investment showed that the U.S. trade deficit with Mexico and Canada increased from $17.0 billion to $177.2 billion between 1993 and 2013 and supplanted 851,700 U.S. jobs. [84] Many analysts explain these different results by pointing out the “two-speed” nature of the Mexican economy, where NAFTA has led foreign investment growth, high-tech production and rising wages in the industrial north, while the largely agricultural south has remained disconnected from this new economy. University of Pennsylvania economist Mauro Guillen argued that Mexico`s growing inequality is due to NAFTA workers receiving much higher wages from trade-related activities in the north.