<P> The U.S. Constitution (Article II, Section 1, Clause 6) provides that "In Case of the Removal of the President from Office, or of his Death, Resignation, or Inability to discharge the Powers and Duties of the said Office, the Same shall devolve on the Vice President, ..." Initially, it was unclear whether this meant the vice president became the new president or merely an acting president . This was first tested in 1841 with the death of President William Henry Harrison . Harrison's vice president, John Tyler, asserted that he had succeeded to the full presidential office, powers, and title, and declined to acknowledge documents referring to him as "Acting President ." Despite some strong calls against it, Tyler took the oath of office as the nation's tenth President . Although some in Congress denounced Tyler's claim as a violation of the Constitution, it was not challenged legally, and so the Tyler precedent of full succession was established . This was made explicit by Section 1 of the Twenty - fifth Amendment to the United States Constitution, ratified in 1967 . In total, nine incumbent Vice Presidents have succeeded to the presidency . In addition to Tyler they are Millard Fillmore, Andrew Johnson, Chester A. Arthur, Theodore Roosevelt, Calvin Coolidge, Harry S. Truman, Lyndon B. Johnson, and Gerald Ford . </P> <P> Another issue was who had the power to declare that an incapacitated president is unable to discharge his duties . This question had arisen most recently with the illnesses of President Dwight D. Eisenhower . Sections 3 and 4 of the amendment provide means for the vice president to become acting president upon the temporary disability of the president . Section 3 deals with self - declared incapacity of the president . Section 4 deals with incapacity declared by the joint action of the vice president and of a majority of the Cabinet or of such other body as Congress may by law provide . While Section 4 has never been invoked, Section 3 has been invoked three times: on July 13, 1985 when Ronald Reagan underwent surgery to remove cancerous polyps from his colon, and twice more on June 29, 2002 and July 21, 2007 when George W. Bush underwent colonoscopy procedures requiring sedation . Prior to this amendment, Vice President Richard Nixon informally assumed some of President Dwight Eisenhower's duties for several weeks on each of three occasions when Eisenhower was ill . </P> <P> The extent of any informal roles and functions of the vice president depend on the specific relationship between the president and the vice president, but often include tasks such as drafter and spokesperson for the administration's policies, adviser to the president, and being a symbol of American concern or support . The influence of the vice president in this role depends almost entirely on the characteristics of the particular administration . Dick Cheney, for instance, was widely regarded as one of President George W. Bush's closest confidants . Al Gore was an important adviser to President Bill Clinton on matters of foreign policy and the environment . Often, vice presidents are chosen to act as a "balance" to the president, taking either more moderate or radical positions on issues . </P> <P> Under the American system the president is both head of state and head of government, and the ceremonial duties of the former position are often delegated to the vice president . The vice president is often assigned the ceremonial duties of representing the president and the government at state funerals or other functions in the United States . This often is the most visible role of the vice president, and has occasionally been the subject of ridicule, such as during the vice presidency of George H.W. Bush . The vice president may meet with other heads of state or attend state funerals in other countries, at times when the administration wishes to demonstrate concern or support but cannot send the president personally . </P>

What is the job of the us vice president