Rep Burchett said the way it works is the politicians come to DC all fresh-faced and ready to do business, but along the way they are at some meeting, some party, some bar and they meet a person of interest ... they get to talking and one thing leads to another.
Later when some bill comes up, some lobbyist slides up to the fresh-faced politician and whispers, we know what you did ... and the politician votes as instructed.
I am sure that is exactly how it goes down. The rats seem to regularly catch pubbies in sexual peccadillos.