Three major candidates ran in the primary, including former vice president Joe Biden, senator Bernie Sanders from Vermont, and representative Tulsi Gabbard from Hawaii's 2nd district.

In a distant third was former mayor Michael Bloomberg, who came close to 10%, even though he had suspended his campaign nearly two weeks before and had issued an official withdrawal with the state, still remaining on the ballot.

[2] In a stark contrast from 2016, Sanders' strength was reliant primarily on non-white and Hispanic voters, whom Biden won by only 47-45 and 45–44, respectively.

In the closed primary, candidates had to meet a threshold of 15 percent at the congressional district or statewide level in order to be considered viable for delegates.

Candidates that had filed a formal withdrawal with the office remained on the ballot because it had already been printed but their votes were not individually published in the final canvass, making them effectively ineligible.

[7] Running Withdrawn Formal withdrawal (ineligible) 0Michael Bloomberg0Amy Klobuchar0Tom Steyer0John Delaney0Cory Booker0Michael Bennet 58,79710,3331,381505494394 9.591.680.230.080.080.06 Arizona was a hotly contested state throughout both the primary and general election seasons due to its rapidly diversifying electorate.

[22] The results of the primary would be reflected in the general election: Biden would end up winning Arizona by 10,457 votes, the first Democrat to do so since Bill Clinton in 1996 and only the second since Harry S. Truman in 1948.