LBJ "hacked" the American Senate, understanding its operations better than anyone perhaps ever. He further understood its role in American politics, and the impact of American politics upon it. This 3rd volume of Caro's multi-volume biography covers LBJ's adoption of the vice-presidency, why his hopes of dominating JFK from that position failed (tldr; Kennedy was much, much smarter that Johnson understood), and Johnson's extraordinary transition to the Presidency on Kennedy's assassination.
The book would be outstanding simply for its sketches of JFK and RFK, figures secondary to its primary focus. Taken as a whole it's required required reading for anyone thinking they understood politics.