Open Primaries Keep Democracy on Track

What Are Open and Closed Primaries?

Open primaries allow voters to choose which primary they would like to vote in on an election-by-election basis. It does not require swing and independent voters to register with a particular party before choosing a ballot. Closed primaries require voters to register with a party for the privilege of voting in their primary.

The deadlines for declaring party affiliation can eliminate game-time decisions for voters on the fence about whether they want to vote for a primary candidate. Late breaking news means little if seeing voters cannot change their party affiliation within a reasonable time before a primary.

How Do Open, Closed, and Semi-Closed Differ?

Let’s imagine a where a completely undecided voter who has no partisan affiliation wants to go vote in a primary for the next presidential election. They have some left-leaning opinions, some right-leaning opinions, but they feel drawn to a particular candidate that they want to vote for in November.

In an open primary state, this voter would be able to go in on the primary election day, pick which party’s ballot they want to vote on and vote for the candidate that they want to see on the ballot in November. In a closed primary state, this voter would be required to register with a party, which is in some states allowed on election day and in others must be done in advance, to vote for a candidate on a party’s ballot. In a semi-closed primary state, this voter would be free to choose a ballot without registering, but registered voters with either party would be restricted to their declared party’s ballot.

What About Crossover Voting?

The main pushback against open primaries is the potential for crossover voting from the opposite political party. According to empirical and anecdotal studies such as those by Mark Trautmann, crossover voting is a possibility.¹ Crossover voting happens when members of one party vote in another party’s primary to pick a weaker candidate. While this is a possibility, it would be cancelled out by both parties equally doing so, and historically it has been rarely done and ineffective in producing weaker candidates. Run Down the Middle believes these concerns are substantially outweighed by letting voters choose their primary ticket when they vote without losing their partisan independence.

How Do Open Primaries Help Independents?

Open primaries give independents a voice in who the major party candidates are that they vote for in the general election. When independents are excluded, party hardliners can and do select polarizing ideological candidates that increasingly don’t represent the growing number of independents. Open primaries solve this problem by giving independents to vote for candidates that they want on the ballot from a particular party.

What Is the Let America Vote Act?

The Let America Vote Act, HR 155, requires that federal elections be subject to open primaries by all parties and that unaffiliated voters are protected from automatic registration with a party, to preserve their good faith independence from the major political parties. The Let America Vote Act also encourages states to open their primaries by granting funds for federal election administration.²

RDM supports this legislation, which will only apply to federal elections. The middle should not have to veer to the right or left by registering with a political party just to vote in a primary election.

Key Takeaways

• Open primaries allow independent voters to choose the ballot that they want to select candidates from.
• Closed primaries restrict voting to registered party members, which may require advance registration.
• Semi-closed primaries require registered party members to vote with their own party, but allow independents to choose.
• Crossover voting is possible with open primaries, but it is rare and unlikely to effect the primary result.
• Independents benefit from open primary systems by being able to choose the candidates for the general election, rather than leaving it to the party hardliners.
• The Let America Vote Act is a proposed law that would require open primaries for all elections to federal office, with funding incentives for states that implement open primaries.

Common Questions About Open Primaries

What is the difference between an open and closed primary?

Open primaries allow every voter regardless of partisan affiliation to vote on the party ballot of their choice. Closed primaries restrict only registered party members to vote in the primary.

What is a semi-closed primary?

A semi-closed primary requires a voter registered with a party to vote with that party while allowing independents and unaffiliated voters to choose their ballot.

Does open primary voting let the other party interfere?

While it is possible to have crossover voting, Mark Trautmann shows in his empirical research that attempts to use crossover voting to influence a primary are rare and largely unsuccessful at swaying the result of the primary.

Which states have open primaries?

Primary types depend on both state and party. 14 states have open primaries for both parties, 17 states have closed primaries for both parties, however 5 of these allow same day registration. A full list with a helpful map can be found in this Ballotpedia article.³

What is the Let America Vote Act?

The Let America Vote Act is a proposed Congressional law that would require all primary elections for federal office to be open primaries. It also provides election administration funding incentives to states that implement these changes.

Sources

1. Trautmann, Mark (2024) “Cross-Party Voting in 21st Century Presidential Primaries: A Social and Empirical Analysis,” The Dialogue: Vol. 1: Iss. 1, Article 3. Available at: https://scholar.smu.edu/thedialogue/vol1/iss1/3 ↩︎
2. Harrison, Eric. “The Let America Vote Act: What It Is, Why It Matters, and What It Means for Independent Voters.” Independentcenter.Org, Independent Center, 29 Apr. 2026, https://www.independentcenter.org/articles/the-let-america-vote-act-what-it-is-why-it-matters-and-what-it-means-for-independent-voters. ↩︎
3. Ballotpedia. “Primary Election Types by State.” Ballotpedia, Aug. 2026, https://ballotpedia.org/Primary_election_types_by_state. ↩︎

About the author

Michael Stage

Economics and political science out of DePaul, by way of Austin. Believes in a government that is responsive because it is built to be.