I lifted the following from the Wikipedia write-up on Ehrlichman's novel, "The Company."
Key to real-life inspirations:
Director of Central Intelligence William Martin - DCI Richard Helms
President Richard "Dick" Monckton of Illinois - President Richard Nixon of California
President Esker Scott "ESA" Anderson of Oregon - President Lyndon B. Johnson of Texas
President William Arthur "Bill" Curry of New York - President John F. Kennedy of
Vice President Edward Miller "Ed" Gilley of Pennsylvania - Vice President Hubert
Humphrey of Minnesota
Governor Thomas J. Froville of New Jersey - Governor Nelson Rockefeller of New York
National Security Advisor Dr. Carl Tessler - National Security Advisor Dr. Henry
President's Monckton Aide Frank Flaherty - White House Chief of Staff H. R. Haldeman
FBI Director Elmer Morse - FBI Director J. Edgar Hoover
Those of you who have a firm grasp on that part of history, please add historical figures behind more of the characters. I have an inkling who some of them are, but I don't want to guess and pass on wrong information.