"What do Dick Cheney and Rahm Emanuel have in common? Aside from polarizing personalities, both served as chief of staff to the president of the United States--as did Donald Rumsfeld, Leon Panetta, and a relative handful of others. The chiefs of staff, often referred to as 'the gatekeepers,' wield tremendous power in Washington and beyond; they decide who is allowed to see the president, negotiate with Congress to push POTUS's agenda, and--most crucially--enjoy unparalleled access to the leader of the free world"--Amazon.co