In 1952, President Harry S. Truman lost the New Hampshire primary to Tennessee Senator Estes Kefauver and decided not to seek re-election. Kefauver was very unpopular among leading democrats so Truman suggested that Illinois Governor Adlai Stevenson II should seek the Democratic nomination. Stevenson declined. A draft Stevenson campaign was launched and still he refused.
Kefauver entered the convention with the most primaries primary wins but lost the nomination to Stevenson who then lost the general election to Dwight D Eisenhower.
Four years later, 1956, Stevenson campaigned in earnest and got the nomination again. Convention delegates chose the aforementioned Kefauver to be his running mate over the upstart John F Kennedy. Popular amongst the youth, his proposed policies foreshadowed some of the policies of his successors.
But, Eisenhower was too popular and the economy of the era was too strong. Stevenson lost in a landslide with Eisenhower getting 57% of the vote to Stevenson's 42%.