1948 Democratic Party presidential primaries  The 1948 Democratic presidential primaries were the selection process by which voters of the Democratic Party chose its nominee for President of the United States in the 1948 U.S. presidential election. Incumbent President Harry S. Truman was selected as the nominee through a series of primary elections and caucuses culminating in the 1948 Democratic National Convention held from July 12 to July 14, 1948, in Philadelphia, Pennsylvania. As a sitting President, his nomination was secured.