Democratic primary

This was the first time that candidates were chosen through primaries. New Jersey Governor Woodrow Wilson ran to become the nominee, and faced the opposition of Speaker of the United States House of Representatives Champ Clark. Wilson defeated Clark and was nominated during the convention. He then won the general election with a landslide victory.

Democratic incumbent President Woodrow Wilson ran for re-election, and faced no major opposition in the primaries.

Former United States Secretary of the Treasury William Gibbs McAdoo and Ohio Governor James Cox were the main candidates. Though William Gibbs McAdoo won a vast majority of states, Cox won the nomination on the 22nd ballot at the convention. Cox went on to lose the election to Republican candidate Warren Harding.

Former United States Secretary of the Treasury William Gibbs McAdoo, 1920 candidate James Cox and Henry Ford were the main candidates. Though William Gibbs McAdoo won a vast majority of states, and well more than half of the popular vote, in those twelve states that held primary elections, it meant little to his performance nationwide. Once at the convention, the party was deadlocked for 102 straight ballots, before dark horse candidate John W. Davis, (who wasn't even a formal candidate when he arrived at the convention) was chosen on the 103rd ballot. Davis went on to lose the election to Republican candidate Calvin Coolidge.

...
Wikipedia