George W. Bush was NOT eligible to be elected again as President in 2012.
He had served two full terms in office as President, having been elected in 2000 and again in 2004, serving in office from January 20, 2001 to January 20, 2009.
The 22nd Amendment of the US Constitution set term limits for the office of President. The 22nd Amendment, Section 1, reads as follows:
No person shall be elected to the office of the President more than twice, and no person who has held the office of President, or acted as President, for more than two years of a term to which some other person was elected President shall be elected to the office of the President more than once. But this Article shall not apply to any person holding the office of President, when this Article was proposed by the Congress, and shall not prevent any person who may be holding the office of President, or acting as President, during the term within which this Article becomes operative from holding the office of President or acting as President during the remainder of such term.
The 22nd Amendment was passed by Congress in 1947 and ratified in 1951. It was enacted following the period during which Franklin Delano Roosevelt (FDR) was elected to the Presidency in four consecutive elections -- 1932, 1946, 1940, and 1944. (He died in April, 1945, while in office during his fourth term.) FDR was the first (and only) president to serve more than two terms. With the passage of the 22nd Amendment, no president can be elected more than twice to the office. A president could serve additional years beyond two terms if he came into the office initially after the death or resignation of a president. So, for instance, Lyndon Johnson, who succeeded John F. Kennedy (JFK) after JFK's assassination in 1963, could have been elected two times after that. But after finishing JFK's term and being elected in 1964, Johnson chose not to run again in 1968.
