Arizona is one of 21 states with a mixed primary system. The primary is considered semi-closed. Unaffiliated voters may choose which party's primary they will vote in, but voters registered with a party can only vote in that party's primary.
- National Conference of State Legislatures Website, "State Primary Election Types," accessed January 6, 2014
- Fair Vote, "Congressional and Presidential Primaries: Open, Closed, Semi-Closed, and 'Top Two,'" accessed January 6, 2014
- Ballotpedia research conducted December 26, 2013, through January 3, 2014, researching and analyzing various state websites and codes.