If the U.S. doesn't sign the TPP, it is not bound by it, regardless of how many other countries support it. But, e.g. Massachusetts was bound by the Defense of Marriage Act for ~20 years even though a majority of its Congressmen and both of its Senators voted against it. That's not sovereignty.

EU rules are like U.S. federal laws, not WTO treaties. Member states can be bound by them even if their representatives vote against them.