I have been a regular supporter of Keith Ellison over more than a decade and a strong supporter of Bernie Sanders.
However I disagree with the position of both people on the TPP. The full text of the agreement is now available on a New Zealand government website. You can read the labor chapter, which I agree should be a concern, and I think you will find that it is not so terrible as the campaign against TPP has claimed. Similarly there is a long chapter on environmental concerns which seems to cover most of the issues.
It is, I think, true that in the US, trade agreements have resulted in some winners and some losers. For example, in the West and Midwest, agriculture benefits from increased trade, while manufacturing has suffered. However, though I know that people blame growing income inequality on trade agreements, I think that the more important causes are unfair taxing and technological change. Those concerns are better addressed in my opinion by better tax laws which make the rich pay a fair share and more funds for training people to work in new industries and to make digital technologies universally available.
In the larger picture, trade has eliminated poverty for millions of people throughout the world over the last decades. And, in my opinion, by creating mutual dependencies between nations, trade agreements reduce the likelihood of wars.
I hope that Keith Ellison will reconsider his opposition to the TPP.