In 2015-16, Open Primaries partnered with former Phoenix Mayor Paul Johnson on a campaign to place a nonpartisan primaries referendum on the 2016 ballot. Although the campaign ultimately failed to to get a measure on the ballot, it did make strides in assembling a strong coalition of independent activists, elected officials, business leaders and Latino activists from across the political spectrum.
- Democratic congressional and state primaries: mixed
- Republican congressional and state primaries: mixed
- Democratic Presidential primary: closed
- Republican Presidential primary: closed
- Optional party affiliation. Voters are given the option to affiliate or not to affiliate with a political party on the registration form.
- 36% of registered voters in Arizona are unaffiliated or independent.
Details of state and local primary elections:
- Unaffiliated voters may choose which party's ballot they will vote on.
- Party members may only vote on their party's ballot.
- Voter registration closes 29 days before the primary election.