The New York Times has the article Trade Pact With Asia Faces Imposing Hurdle: Midterm Politics. The authors of the article are  Mark Landler and Jonathan Weisman.  If the editors have not severely changed the article they wrote, the gist of their explanation for opposition to the TPP comes in the following excerpt from the article:

Many Democrats typically oppose trade deals, along with their allies in unions and environmental and consumer groups, because they do not want to encourage free-trade agreements that they say would siphon off manufacturing jobs in the United States and create pollution.

This has got to be one of the most deceptive paragraphs and articles that have ever appeared in The New York Times.  This rivals the false article leading up to the Iraq War that claimed weapons of mass destruction in Iraq were the reason for the war.  The author of those articles was fired.  The Democrats who are opposed to this treaty have evidence that the secret negotiations have led to sections that allow corporations to sue governments over any regulation that harms the corporations’ interests.  This would make it impossible for countries to enforce regulations on labor standards,  environment policies, or product safety.  Also included in the treaty are huge concessions to corporations on intellectual property rights that protect a corporation’s monopolies on technology that are beyond all reason.  No wonder our 11 trading partners are having a hard time accepting these parts of the treaty.

For a better explanation of what is wrong with TPP, you could search this blog for the phrase “TPP”.  One of the article you will find is Bill Moyers: The Corporate Plot That Obama and Corporate Lobbyists Don’t Want You to Know About.