It can be a very powerful position, and the Chief of Staff is sometimes even dubbed "The Most Powerful Man in Washington." Some have even suggested that a powerful Chief of Staff dealing with a "hands off" president who decides not to become involved in the minutiæ of government, can become a quasi-prime minister. Such prime ministers exist in some presidential systems, with the Prime Minister de facto running the system of government and the President standing back and setting broad policy agendas. James Baker and Donald Regan were seen as prime ministerial-style Chiefs of Staff during the Reagan presidency. Howard Baker[?], who suceeded Regan, was critical of this system and what is sometimes called the Imperial Presidency.
By contrast, Andrew Card, the Chief of Staff within the administration of George W. Bush is not regarded as a very powerful figure, in large part because Bush appears to deal directly with his Cabinet secretaries.
The duties of the position can vary greatly from administration to administration, but generally the Chief of Staff is responsible overseeing the actions of other members of White House staff, managing the president's timetable, and controlling outsiders' access to the president. This last duty has often earned the Chief of Staff the nickname of the "Gatekeeper."
Informally, the Chief of Staff is often one of the President's closest political advisors, and a close friend.
Not every President has had a formal Chief of Staff. Presidents Kennedy and Johnson never did, nor did President Carter until the very end of his term.
wikipedia.org dumped 2003-03-17 with terodump