George Washington
At the end of his second term, Washington retired for personal and political reasons, fatigued and disgusted with personal attacks, and to assure a truly contested presidential election could be held. He did not feel bound to a two-term limit, but his retirement ultimately set precedent. The two-term limit to the presidency was formalized with the 1951 adoption of the Twenty-second Amendment to the United States Constitution. Washington is often credited with setting the principal of a two-term presidency, but it was Thomas Jefferson who first refused to run for a third term on political grounds.
Term limits in the United States
In 1940, Franklin D. Roosevelt (president, 1933–1945) became the only president to break the tradition, winning a third term in 1940 and a fourth term in 1944. This gave rise to a successful move to formalize the traditional two-term limit by amending the U.S. Constitution. As ratified in 1951, the Twenty-Second Amendment provides that "no person shall be elected to the office of President more than twice". The new Amendment explicitly did not apply to the incumbent, President Harry S. Truman. However, Truman's close advisors convinced him not to seek a third term regardless, pointing to his age, his failing abilities, and his poor showing in the polls.