Constitutional law: Government structure - Executive branch (Part 3 of 3)

When the first president, George Washington, announced in his Farewell Address that he was not running for a third term, he established a "two-terms then out" precedent. Precedent became tradition after Thomas Jefferson publicly embraced the principle a decade later during his second term, as did his two immediate successors, James Madison and James Monroe. In spite of the strong two-term tradition, Ulysses S. Grant unsuccessfully sought a non-consecutive third term in 1880.

In 1940, after leading the nation through the Great Depression, Franklin Roosevelt was elected to a third term, breaking the long-standing precedent. Four years later, with the U.S. engaged in World War II, he was re-elected again despite his declining physical health; he died 82 days into his fourth term on April 12, 1945.

In response to the unprecedented length of Roosevelt's presidency, the Twenty-second Amendment was adopted in 1951. The amendment bars anyone from being elected president more than twice, or once if that person served more than two years (24 months) of another president's four-year term. Harry S. Truman, president when this term limit came into force, was exempted from its limitations, and briefly sought a second full term—to which he would have otherwise been ineligible for election, as he had been president for more than two years of Roosevelt's fourth term—before he withdrew from the 1952 election.

Since the amendment's adoption, five presidents have served two full terms: Dwight D Eisenhower, Ronald Reagan, Bill Clinton, George W Bush, and Barack Obama. Jimmy Carter, George H W Bush and Donald Trump each sought a second term but were defeated. Richard Nixon was elected to a second term, but resigned before completing it. Lyndon B. Johnson, having held the presidency for one full term in addition to only 14 months of John F Kennedy's unexpired term, was eligible for a second full term in 1968, but he withdrew from the Democratic primary. Additionally, Gerald Ford, who served out the last two years and five months of Nixon's second term, sought a full term but was defeated by Jimmy Carter in the 1976 election.