There are one million executive actions and things he could be doing from the Oval Office to signal to voters that he's fighting for them. Congress is locked up with coporate money but he could bypass it in many areas. Then he could also play old fashioned politics and apply pressure. It wouldn't work but he could be fighting and showing voters he's doing something.

The Dems are already a center-right party. Moving to "the middle" in a modern liberal democracy would be them moving left.

But, you're right, and he will probably move further right to try and appease the Republicans and it won't work. It is the classic ratcheting of America rightward since the seventies. Every presidency the country goes three steps right, and it can't be turned back.

Hence the never-ending death spiral.