Free trade has been the driving force  that powers the global economy.
The TPP trade agreement provided a sounder basis for resolving issues related to intellectual property (a major concern for US businesses) and incorporated protections for workers in less developed member states.
A related issue is whether NAFTA has benefited the US - clearly it has - trade between the 3 countries has increased significantly. Mexico's workforce has been rewarded with better paying jobs, Canada's industry has had a stable trading partner and the US consumer has been blessed with materials and products that are provided at lower cost (without dependence upon only subsistence wage driven products).
The issue, of course is that workers in the US have lost the ability to compete (here I agree totally with the left's POV that persons deprived of their livelihood need to be provided with a safety net of some magnitude to make them whole- retraining only goes so far).
I totally disagree with the creation of barriers that subsidize inefficient (i.e. sugar production) or uneconomic/polluting (i.e. coal mining) enterprises at the expense of wiser and safer choices (so perhaps I don't disagree with the left  that much on this issue).