Their real high was taking down Nixon with Watergate. It was the apex of their power, which has slowly waned with the rise of the new Internet media and the expansion of cable news and programming and talk radio. The big three TV networks or the national news mediea no longer have a monopoly on where Americans get their information.
Now, they're on the verge of losing all that power, even in their own perception, and there is no tactic or slander the MSM won't pull out of the bag over the next two weeks to prevent it.
I agree with you that if the Reps hold on to both houses in the midterms, it will be devastating for them and their self-image. The worse thing that can happen to someone with a huge ego is to realize that he/she is irrelevant. Unfortunately, the folks inside the Beltway and in Congress still believe that they matter and will be the last to let go of that illusion.
I think the happiest time in my lib, yellow dog dem's friend's life was Watergate. She and her lib friends had a party on the anniversary every year. I do not joke.
I'm not sure when they finally gave that up. Maybe during the Clinton years when they thought they had it back.