U.S. President Barack Obama acknowledges supporters during an election campaign rally in Aurora, Colorado, November 4, 2012. (Photo: Reuters)
+ 1932-1945: Franklin Roosevelt (Democrat)
Re-elected for the fourth time in 1940 -- the country's two-year term limit was adopted in 1951 -- he died on April 12, 1945, less than a month before the end of the war in Europe.
+ 1945-1952: Harry Truman (Democrat)
As vice president, he took office after Roosevelt's death and was re-elected in 1948.
+ 1952-1960: Dwight Eisenhower (Republican)
+ 1960-1963: John Kennedy (Democrat)
Assassinated in Dallas on November 22, 1963.
+ 1963-1968: Lyndon Johnson (Democrat)
As vice president, he took office in 1963 after Kennedy's death and was re-elected in 1964.
+ 1968-1974: Richard Nixon (Republican)
Re-elected in 1972, he resigned in 1974 over the Watergate scandal.
+ 1974-1976: Gerald Ford (Republican)
As vice president, he replaced Nixon following his resignation. To this day, he is the only president who was never elected after losing his 1976 bid to Jimmy Carter.
+ 1976-1980: Jimmy Carter (Democrat)
+ 1980-1988: Ronald Reagan (Republican)
+ 1988-1992: George Bush (Republican)
+ 1992-2000: Bill Clinton (Democrat)
Clinton is the only Democrat to serve two terms in the White House since the end of World War II. Obama is vying to become the second.
+ 2000-2008: George W. Bush (Republican)
+ 2008 - : Barack Obama (Democrat)