Shawn Griffiths
Six states are holding statewide primary elections on Tuesday, June 2: California, Iowa, Montana, New Jersey, New Mexico, and South Dakota. But for independent voters, the rules are not even close to uniform.
In one state, every voter gets the same candidate choices, regardless of party preference or political affiliation. In others, independents must pick a party ballot, affiliate with a party, or are blocked from key contests entirely.
That means the biggest question for many voters on June 2 is not just who is on the ballot. It is whether they have equal voting rights without joining a party.
California: Top Two Nonpartisan Open Primary
California is the only state on this list that uses a nonpartisan primary system in which all candidates and voters participate on the same primary ballot, regardless of party. The top two vote-getters then move on to the general election.
This primary system is used for US Senate, US House, statewide executive offices, and state legislative races. And because California has a universal vote-by-mail system, every registered voter is sent the same ballot, and they can choose from any candidate they want.
This primary system was adopted by California voters in 2010 under Proposition 14, which was sponsored by the Independent Voter Project.
Shawn Griffiths
It is of the most straightforward and inclusive systems for independent voters, many of whom are registered No Party Preference. But even if an independent is registered with a party, it doesn’t change anything because all voters are treated the same.
They do not need to request a party ballot, switch registration, or affiliate with a party to participate in these elections.
California’s system is not a party-nominated system like what is used in most states. It is a voter-nominated system. The distinction alone should inform voters on who has the most influence over primary outcomes.
It’s not the parties. It’s voters. The primary is the first round of the election, not a party gatekeeping contest.
Shawn Griffiths
Iowa: Partially Open, But Independents Must Declare a Party
Iowa holds Democratic and Republican partisan primaries. NCSL categorizes Iowa as a partially open primary state because voters can publicly change party affiliation for the purpose of voting in a primary.
However, party declaration is still a condition to vote in these taxpayer-funded elections. For this reason, it is more accurate to say Iowa primaries are closed.
For independent voters, participation is possible, but not as independents. Iowa voters must be registered with a political party to vote in a party primary. Voters are allowed to re-register with a political party on Election Day.
Iowa’s June 2 ballot includes major contests for governor, US Senate, and US House. With the retirements of Gov. Kim Reynolds and Sen. Joni Ernst, elections for both officers are open-seat contests.
Bottom line for independent voters: Their participation is conditioned on joining a party. They can still participate, but they have to change their voter registration, adding an additional requirement to vote in taxpayer-funded elections.
They are also restricted to a Republican or Democratic ballot.
Montana: Open Primary, Pick One Party Ballot
Montana has an open partisan primary system. The state does not require voters to register by party, and voters can select the primary ballot of their choice when they go to vote.
While independent voters can participate, it is not a voter-nominated process like in California. It is a party-nominated system. Voters pick a party ballot and can only vote for the candidates on that party’s ballot.
That gives independent voters access but still forces a party choice for the primary.
Montana’s June 2 primary includes US Senate, US House, and state legislative races, with high-stakes contests following the exits of Republican incumbents Steve Daines and Ryan Zinke from their current offices.
Bottom line for independent voters: They can vote without joining a party, but they have to pick a party’s ballot and stick to that party’s candidates.
New Jersey: Closed Primary—Join A Party or Don’t Vote.
New Jersey is a closed primary state. Voters have to be a registered party member in order to vote in these taxpayer-funded elections. If independents are willing to declare a party, they can vote—even on Election Day.
But it is still a condition to their right to vote.
It’s worth noting that the Independent Voter Project filed a lawsuit on behalf of 7 New Jersey plaintiffs in 2014, challenging the state’s use of closed primary elections. At the time, nearly half the state was registered independent of either major party.
This equaled 2.6 million independent voters who the state told in its court filings had to “join a party or don’t vote.” Plaintiffs argued that closed primaries violated their First and Fourteenth Amendment rights.
In 2026, New Jersey’s June 2 primary applies mainly to congressional races, which are drawn to be safe mostly for Democrats. State legislative and executive elections are held in odd-numbered years.
Bottom line for independent voters: The state does not recognize their right to vote in taxpayer-funded primary elections. They have to join a party to have meaningful participation in elections.
New Mexico: Independents Can Vote in The First Semi-Open Primary
New Mexico adopted a semi-open partisan primary system in 2025 and is using it for the first time in 2026. This system allows independent voters to pick a qualified political party’s ballot while registered party members have to vote in their party’s primary.
This is a major shift for independent voters. Previously, New Mexico had closed primaries that barred their participation and they did not have a meaningful say in who represented them in most contests.
Now, independents can participate in a major-party primary while keeping their registration status. The new rules are the result of a decade of reform activism and multiple attempts to give independent voters access to the ballot.
Shawn Griffiths
New Mexico’s June 2 ballot includes races for governor, US Senate, US House, and other offices.
Bottom line for independent voters: They can vote in a major-party primary without changing their registration. But they must choose one party ballot, and that ballot choice is public (though actual votes remain private).
South Dakota: Partially Closed, GOP Primary Closed to Independents
South Dakota uses a semi-closed partisan primary system. State law allows political parties to decide whether independent voters can participate in their primaries.
In 2026, the Democratic Party’s primary is open to registered party members and independent/no party affiliation voters. The Libertarian Party’s primary is also open to independent voters.
But if voters want to select a Republican candidate in a heavily Republican state, they are out of luck. The GOP keeps their primary closed to registered party members only.
That matters because the state’s most consequential races are often inside the GOP primary. AP reports that South Dakota’s June 2 ballot includes competitive Republican primaries for governor and US House, along with a US Senate race.
Bottom line for independent voters: They can participate in the Democratic or Libertarian primary, but not the Republican primary unless they are registered Republican.