Biden has shrunk from making the case from rejoin the TPP after Trump left the TPP. Might there be any reason why Biden hasn't immediately taken the measures to rejoin it? The TPP was seen as a way to contain China, and I am wondering if there's anything within the TPP that might trouble Biden.
Biden's attitude towards the Trans-Pacific Partnership are not that black-and-white. In 2019, he said:
“I would not join the TPP as it was initially put forward. I would insist that we renegotiate pieces of that with the Pacific nations ... so that we could bring them together to hold China accountable."
So while he might be in favor of the idea of the TPP in general, he is not in favor of doing it the way it was originally negotiated.
What aspects does he want to renegotiate? He further stated:
We have to join with the 40 percent of the world that we had with us and this time make sure that there’s no one sitting at that table doing the deal unless environmentalists are there and labor is there.
Changing an international trade agreement to put more emphasis on social and ecologic concerns is definitely a political pill which is hard to swallow for many of the more conservative people who have a say in this, both domestic and internationally. That could make such a renegotiation a rather challenging effort.
(I originally wrote this as a comment to Phillip's answer, which I've upvoted. However, I ended up thinking that it was a possibly a significant shift from what he intended as an answer, so it would be best put separately).
In addition to what Philipp said, having a trade agreement in the first place can also be a bitter political pill to more lefty people. Certainly NAFTA is a trigger to many left-of-center Canadians. So there is likely a sizable constituency of Biden supporters who are reflectively allergic to such a deal and may or may not come around even if labor and environmentalists are there.
And those labor and environmentalist representatives also will have to take into account their own constituents looking out of a betrayal of principles.