Hillary’s decision to oppose the TPP without even reading the final version is only explicable as one of an ongoing series of efforts to protect her left flank from Bernie Sanders. It is almost certainly unnecessary, it won’t work–given her history, she can’t out-Sanders Sanders–and it is extremely bad policy.
I have to assume she thinks the agreement will pass with purely Republican support, so there is no substantive risk in treating it as a political football. I disagree; given the current state of the GOP, nothing they do can be taken for granted.
If the TPP fails, due in any part to her opposition, and she is elected, what is she going to say to our putative partners to the agreement? Go make a better deal with the Chinese?