John Fitzgerald Kennedy (May 29, 1917 – November 22, 1963), often referred to by his initials JFK or by his nickname Jack, was an American politician who served as the 35th president of the United States from January 1961 until his assassination in November 1963. Stevenson—the 1952 and 1956 presidential nominee—remained very popular in the party, while Johnson also hoped to win the nomination with the support from party leaders. Kennedy's candidacy also faced opposition from former president Harry S. Truman, who was concerned about Kennedy's lack of experience. Kennedy knew that a second ballot could give the nomination to Johnson or someone else, and his well-organized campaign was able to earn the support of just enough delegates to win the presidential nomination on the first ballot.