That is because most of the Republicans in DC actually prefer Biden over Trump. Trump is an outsider. He is not corrupt.
Trump can not be controlled. Therefore, he is dangerous to the status quo.
Everyone of these DC swamp creatures becomes very rich being in DC. They get access to insider information they can use to make themselves wealthy. Especially, if they become a committee chairman. They have lobbyists throwing money and favors at them constantly. They create a PAC to take in millions to get themselves reelected. If they don’t win, they get to keep it. They get to spend that money flying around to get reelected. They get to go on “fact finding” missions to foreign countries.
Which is why Paul Ryan hated Donald Trump so much. Even though they’re on the “same team”.