Primary elections are held in September for Delaware's two major political parties: Democrats and Republicans. Primaries select these party's candidates for the November general election. 

Delaware has closed primaries, meaning that only registered voters from participating parties may vote for their party's candidates. May 24, 2024 is the deadline to change political party affiliation in order to vote the September 10, 2024 State Primary Election for that party.

Refer to the Delaware Department of Elections website for details.