1. Words matter; this isn’t doing nothing.
2. “Use your power” is trickier here than it appears. “If you don’t stop doing things I disapprove of, I will stop doing things I really want that you don’t really care about” isn’t huge leverage.
They have already neutered the non-GOP Trump legislative agenda, via inaction.
nationalreview.com/2018/04/trump-…
One thing he can do is informally constrain the actions of POTUS, via his words.