The whole reason they're not doing anything is that the democrats (who might do something) are in the minority in both the house and senate, so what they can do (without breaking rules and norms) is very limited. The Republicans either don't want to do something because they support what Trump is doing, or they're scared to go against him.

If you get a dozen Republicans who are willing to go against Trump, suddenly the anti-Trump side has a majority, which gives them a massive amount of power to do something.