John Fitzgerald Kennedy (May 29, 1917 – November 22, 1963), often referred to by his initials as JFK or by the nickname Jack, was an American politician who served as the 35th president of the United States from 1961 until his assassination near the end of his third year in office. Kennedy was the youngest person to assume the presidency by election. He was also the youngest president at the end of his tenure, and his lifespan was the shortest of any president. Kennedy served at the height of the Cold War, and the majority of his work as president concerned relations with the Soviet Union and Cuba. A Democrat, he represented Massachusetts in both houses of the U.S. Congress prior to his presidency.