ABRAHAM LINCOLN -- First Inaugural Address, 1861

At a time when all the major European states had hereditary monarchs, the idea of a president with a limited term of office was itself revolutionary. The Constitution vests the executive power in the president. It also provides for the election of a vice president who succeeds to the presidency in case of the death, resignation or incapacitation of the president. While the Constitution spells out in some detail the duties and powers of the president, it does not delegate any specific executive powers to the vice president or to members of the presidential Cabinet or to other federal officials.

Creation of a powerful unitary presidency was the source of some contention in the Constitutional Convention. Several states had experience with executive councils made up of several members, a system that had been followed with considerable success by the Swiss for some years. And Benjamin Franklin urged that a similar system be adopted by the United States. Moreover, many delegates, still smarting under the excesses of executive power wielded by the British king, were wary of a powerful presidency. Nonetheless, advocates of a single president -- operating under strict checks and balances -- carried the day.

In addition to a right of succession, the vice president was made the presiding officer of the Senate. A constitutional amendment adopted in 1967 amplifies the process of presidential succession. It describes the specific conditions under which the vice president is empowered to take over the office of president if the president should become incapacitated. It also provides for resumption of the office by the president in the event of his or her recovery. In addition, the amendment enables the president to name a vice president, with congressional approval, when the second office is vacated. This 25th Amendment to the Constitution was put into practice twice in 1974: when Vice President Spiro T. Agnew resigned and was replaced by Gerald R. Ford; and when, after President Richard Nixon's resignation, President Ford nominated and Congress confirmed former New York governor Nelson A. Rockefeller as vice president.

The Constitution gives Congress the power to establish the order of succession after the vice president. At present, in the event both the president and vice president vacate their offices, the speaker of the House of Representatives would assume the presidency. Next comes the president pro tempore of the Senate (a senator elected by that body to preside in the absence of the vice president), and then Cabinet officers in designated order.

The seat of government, which moved in 1800 to Washington, D.C. (the District of Columbia), is a federal enclave on the eastern seaboard. The White House, both residence and office of the president, is located there. Although land for the federal capital was ceded by the states of Maryland and Virginia, the present District of Columbia occupies only the area given by Maryland; the Virginia sector, unused by the government for half a century, reverted to Virginia in 1846.

The Constitution requires the president to be a native-born American citizen at least 35 years of age. Candidates for the presidency are chosen by political parties several months before the presidential election, which is held every four years (in years divisible evenly by four) on the first Tuesday after the first Monday in November.

The method of electing the president is peculiar to the American system. Although the names of the candidates appear on the ballots, technically the people of each state do not vote directly for the president (and vice president). Instead, they select a slate of presidential electors, equal to the number of senators and representatives each state has in Congress. The candidate with the highest number of votes in each state wins all the electoral votes of that state.

The electors of all 50 states and the District of Columbia -- a total of 538 persons -- compose what is known as the Electoral College. Under the terms of the Constitution, the College never meets as a body. Instead, the electors gather in the state capitals shortly after the election and cast their votes for the candidate with the largest number of popular votes in their respective states. To be successful, a candidate for the presidency must receive 270 votes. The Constitution stipulates that if no candidate has a majority, the decision shall be made by the House of Representatives, with all members from a state voting as a unit. In this event, each state and the District of Columbia would be allotted one vote only.

The presidential term of four years begins on January 20 (it was changed from March by the 20th Amendment, ratified in 1933) following a November election. The president starts his or her official duties with an inauguration ceremony, traditionally held on the steps of the U.S. Capitol, where Congress meets. The president publicly takes an oath of office, which is traditionally administered by the chief justice of the United States. The words are prescribed in Article II of the Constitution:

The oath-taking ceremony is usually followed by an inaugural address in which the new president outlines the policies and plans of his or her administration.