The Cabinet is a part of the executive branch of the U.S. federal government consisting of the heads of federal executive departments. Despite having evolved as one of the most powerful organs of the contemporary U.S. government, the term "Cabinet" does not appear in the U.S. Constitution, where reference is made only to the heads of departments.

Article Two of the Constitution provides that the President can require "the opinion, in writing, of the principal officer in each of the executive departments, upon any subject relating to the duties of their respective offices." The 25th Amendment provides that the Vice President and a majority of the principal officers of the departments can transmit a notice that the President is unfit for office.....

The United States Federal Executive Departments are among the oldest primary units of the executive branch of the federal government of the United States—the Departments of State, War, and the Treasury all being established within a few weeks of each other in 1789.

The heads of the federal executive departments are the members of the traditional Cabinet; since 1792, they have, by statutory specification, constituted a line of succession, after the Speaker of the House and the President pro tempore of the Senate, to the presidency in the event of a vacancy in both that office and the vice presidency. The Constitution is referring to these officials when it authorizes the President, in Article II, section 2, to "require the Opinion, in writing, of the principal Officer in each of the executive Departments, upon any Subject relating to the Duties of their respective Offices." In brief, they and their organizations are the administrative arms of the President...

The Executive Office of the President (EOP) consists of the immediate staff of the President of the United States, as well as multiple levels of support staff reporting to the President. The EOP was established by the United States Congress in 1939 after the Brownlow Committee recommended that such a support staff for the President be created. Since its inception under Franklin Roosevelt, the size and influence of the EOP has increased. A CNN article notes that there are about 3,000 EOP staff members as of November 2005...