They don’t have the votes in either house of Congress to actually stop anything. Rhetoric is all they’ve got; what they can do is to make it super-clear how awful Trump’s decision-making is, so that there’s a chance voters will turn out and give them the power to act in the future.
They should be courting the public by making it really clear how awful Trump’s nominees and policies are.
They’re clearly trying to protect somebody. Wish I knew.