What does the Obama administration know about TPP that we don't?

Since so few details have been released, we can only speculate. If you believe that politics is like chess, in that sacrifices are made for long term gain, are there are factors involved besides trade?

President Obama is a centrist, but I’m surprised he’s willing to so thoroughly piss off his base that helped get him elected twice.

One theory I heard was that the trade deal was a compromise about future military opportunities in S.E. Asia, such as maintaining and increasing our military presence in the region to thwart Chinese threats.

Thoughts?