http://www.washingtonpost.com/blogs/wonkblog/wp/2013/12/11/everything-you-need-to-know-about-the-t***s-pacific-partners 10. What does Congress have to do with this?

The Constitution charges Congress with giving advice and consent on trade agreements. Over the past couple decades, though, Congress has abrogated that right somewhat by granting the president something called "trade promotion authority" or "fast track," which is the right to an up-or-down v**e on the treaty as negotiated by the administration so as to avoid quibbling over line items that would require renegotiation with TPP countries.

That's what Congress is currently fighting over. Republicans and big business generally favor reauthorizing the president's fast track privileges, which expired in 2007, while Democrats concerned with protecting U.S. industries and global health have opposed it or demanded more robust consultation up front in exchange. Without trade promotion authority, the chances of ratification are slim.