The true power on Capitol Hill is the staff. They never go away, they write the bills that the elect don’t read, they are the anonymous sources and they are the conduits of the lobbyists money.
Having dwelled in the "Swamp" during Reagan's administration (and part of Carter's), lobby groups draft their desired legislation, give it to "Their" Congresscritters who then send the proposed legislation to the affected Executive Agencies for their review and analysis (as well as suggested changes). Sometimes the lobby groups bring their legislation to the Executive Agency heads who have "selected staff" conduct the reviews...., then the lobby groups can give their draft legislation to "Their" Congresscritters with the endorsement of the affected Executive Agency head...