The correct answer to this open question is the following.
Despite a significant number of voters were convinced that America's trade deals amounted to a giveaway of sovereignty and that the United States should stop tying its own hands and pursue whatever trade policy serves its self-interest, they should also be open to identifying the many benefits free trade brings to the United States.
Of course, in an international free trade negotiation, all the involved parts have to win. This means that there would be disadvantages and sometimes setbacks in some industries. But that is precisely what negotations are for. Specifically, the United States has gained so many positive things by signing NAFTA, the North America Free Trade Agreement between México, the United States, and Canada. The US has had open access to markets that in the past had many restrictions. This means that it has been able to export its goods with minimum or zero taxation.