Worth knowing: Some of the organizations with access to TPP negotiations.
International Brotherhood of Teamsters
United Auto Workers
Audubon Naturalist Society
Boston University
Brookings Institution
American Society of Civil Engineers
American Society of Mechanical Engineers
Consumers Union
Environmental Defense Fund
International Fund for Animal Welfare
The Humane Society of the United States
United Food and Commercial Workers Union
United Steelworkers
Now, granted there are many times more corporate and business-oriented interests being represented than these philanthropic and labor union groups, and none of them have much pull outside (or even really inside) the United States. But it's worth knowing that the groups above have the same access to the process as these business groups.
The source is an anti-TPP blog post from a site whose credibility I have no clue about (it's apparently a religious liberal site), but since it's arguing against TPP, the fact that it provides mitigating information suggests it's legit.