Randall describes today's political system as a combination of blackmail and bribery, with members of Congress beholden to special interests. He contrasts that with how the Senate once worked.
State governments sent senators to Washington to protect the priorities of their state, and they recalled them frequently when those priorities were neglected. A recalled senator was simply replaced with one who would protect the state's interests and its place in the American political system. Then that arrangement got flipped.