History
The difficult duties of the White House Chief of Staff vary greatly from one administration to another. However, the chief of staff has been responsible for overseeing the actions of the White House staff, managing the president's schedule, and deciding who is allowed to meet with the president. Because of these duties, the Chief of Staff has at various times been dubbed "The Gatekeeper" and "The Co-President".
Originally, the duties now performed by the Chief of Staff belonged to the Secretary to the President. In 1946, in response to the rapid growth of the U.S. government's executive branch, the position of Assistant to the President of the United States was established, and charged with the affairs of the White House. In 1961, the president's pre-eminent assistant was designated White House Chief of Staff. "Assistant to the President" became a rank generally shared by the Chief of Staff with such senior aides as Deputy Chiefs of Staff, the White House Counsel, the White House Press Secretary, and others. Prior to the creation of this post, the Chief of Staff's job title was traditionally Appointments Secretary, as with Franklin Delano Roosevelt's aide Edwin "Pa" Watson.
Not every president has had a formal Chief of Staff (e.g., John F. Kennedy did not). Because of the stressful and demanding nature of the job, the average term-of-service for a White House Chief of Staff is a little under 2.5 years. John R. Steelman, under Harry S. Truman, was the last Chief of Staff to serve for an entire presidential administration. Steelman also holds the record for longest-serving Chief of Staff (6 years). Andrew Card and Sherman Adams tie for second-longest (5 years each).
Most White House Chiefs of Staff are former politicians, and many continue their political careers in other senior roles. Richard Nixon's Chief of Staff Alexander Haig became Secretary of State under Ronald Reagan. Gerald Ford's Chief of Staff Dick Cheney became a U.S. Representative for Wyoming, Secretary of Defense under George H. W. Bush and vice president under George W. Bush. Donald Rumsfeld was another Chief of Staff for the Ford administration and subsequently served as Secretary of Defense in the Ford administration and decades later in the George W. Bush administration.
Job duties
The roles of the Chief of Staff are both managerial and advisory and can include the following duties, depending on the President's style of conducting business:[4]
Managerial
* Select key White House staff and supervise them
* Structure the White House staff system
* Control the flow of people into the Oval Office
* Manage the flow of information
Advisory
* Advise the President on issues of politics, policy and management issues
* Protect the interests of the President
* Negotiate with Congress, other members of the executive branch, and extragovernmental political groups to implement the President's agenda
Some, have suggested that a powerful Chief of Staff with a "hands-off" president (who decides not to become involved in the minutiæ of government), can become a de facto prime minister. Such prime ministers exist in some governmental systems, such as France's and Russia's: The prime minister runs the government (operations-wise), while the president remains somewhat aloof from the political process, but personally handling policy matters. Under Ronald Reagan, Donald Regan was seen by many as a prime minister-style Chief of Staff following James Baker. Howard Baker, who succeeded Regan, was critical of this system and what is sometimes known as the "Imperial Presidency."
By contrast, Andrew Card, President George W. Bush's first Chief of Staff, was not regarded as being as powerful. Some have speculated that this was due to Card being "overshadowed" by the influence of Karl Rove, the Senior Adviser and Deputy Chief of Staff who was "the architect" of Bush's political rise. Similarly, President Bill Clinton's Chiefs of Staff were not particularly powerful. Source:
http://en.wikipedia.org/wiki/White_House_Chief_of_Staff