DJT invaded the back rooms of Washington. He was an outsider, who did not know the way the Washington machine works. He threatened the established order. He was a disrupter. And Washington could not abide that.
What made home so effective on the world stage made him an existential threat to the machinery of government that had cosily plotted along for countless years. While his actions had kept China, Russia, North Korea, Iran, etc. guessing what his next move might be, Washington could not take the risk that his disruptive process might transfer to them and uncover what, if it saw the light, might leave people without their cushy jobs, their pensions, their side hustles, their future media careers. That was to be avoided at all costs.
So they waged war, a war they are still waging. Because if their efforts fail, and he manages to overcome the weight of the machine arrayed against him and regains the White House, he will be ready this time. With enough Congressional support, he will hit the ground running and the metaphorical bloodbath in Washington will make their worst nightmares seem like pleasant daydreams.