A write-in candidate is a candidate whose name does not appear on the ballot but seeks election by asking voters to cast a vote for the candidate by physically writing in the person's name on the ballot. Depending on electoral law it may be possible to win an election by winning a sufficient number of such write-in votes, which count equally as if the person were formally listed on the ballot.

The 2024 New Hampshire Democratic presidential primary was held on January 23, 2024, as part of the Democratic Party primaries for the 2024 presidential election. The January New Hampshire primary was not sanctioned by the Democratic National Committee (DNC). The DNC-approved 2024 calendar placed the South Carolina primary first, but New Hampshire state law mandates them to hold the first primary in the country, and a "bipartisan group of state politicians", including the chairs of the Democratic and the Republican parties, announced that the state would preserve this status. Thus, the DNC initially stripped all 33 of the state's delegates that would have been allocated to the Democratic National Convention. The delegates will be allowed to be seated at the convention following the holding of a party-backed firehouse primary on April 27.