Twenty-second Amendment to the United States Constitution
The amendment prohibits any individual who has been elected president twice from being elected again. Under the amendment, an individual who fills an unexpired presidential term lasting greater than two years is also prohibited from winning election as president more than once. Scholars debate whether the amendment prohibits affected individuals from succeeding to the presidency under any circumstances or whether it only applies to presidential elections.
2008 United States presidential election
Incumbent Republican President George W. Bush was ineligible to pursue a third term due to the term limits established by the 22nd Amendment. As neither Bush nor Vice President Dick Cheney sought the presidency, the 2008 election was the first election since 1952 in which neither major party's presidential nominee was the incumbent president or the incumbent vice president. McCain secured the Republican nomination by March 2008, defeating Mitt Romney, Mike Huckabee, and other challengers. The Democratic primaries were marked by a sharp contest between Obama and the initial front-runner, Senator Hillary Clinton. Clinton's victory in the New Hampshire primary made her the first woman to win a major party's presidential primary. After a long primary season, Obama clinched the Democratic nomination in June 2008.