TPPA is signed
The TPPA negotiations were concluded on October 2015 and signed on February 4 of 2016 in New Zealand. For the deal to come into effect, it must be ratified by the legislature. As Professor Haeyoung Lee stated in a previous interview, the TPPA comes into effect 85% of economies (by GDP) ratify it. If the US (57%), Japan (22%), and Australia (6%)[ref]https://www.fas.org/sgp/crs/row/R42344.pdf[/ref] signed the agreement the deal would go into effect. As the largest economy within the TPPA, the fight against it in the United States becomes even more important.
Lori Wallach of Public Citizen explains that given the current resistance to the TPPA in the US Congress, the process will likely get pushed to 2017. That puts even greater importance to the US presidential election as the next president would have to sign the agreement to enact it into law. Lori Wallach explains how candidates polling more than 5% of support all come out against the TPPA. In particular, Bernie Sanders has explicitly come out against it, while Clinton has stated she now opposes the deal after having supported it as Secretary of State. However, as she emphasizes candidates may oppose the agreement during election time but support it when elected president. Thus, the current campaign should focus on candidates pledging to neither send the agreement to Congress or to sign it into law.
Once the TPPA goes into effect, other countries would be able to ascend to the agreement. Thus, the fight against the TPPA is important not only to its current member countries but to all others interested in joining such as South Korea which has publicly expressed interest in joining.
Image above from geopolitics.co written by Dae-Han Song (chief editor, World Current Report)