Pros and cons of open primaries

The pros and cons of open primaries.

Last updated: November 2026

The main pro of open primaries is that every voter can take part; the main con, for parties, is losing control of nominations.

The Independent Voter Project argues that the pros outweigh the cons because primaries are paid for by every taxpayer and often decide the race. Most objections, such as crossover voting, apply to party-ballot open primaries. Nonpartisan open primaries, like California's Top-Two, remove that concern by putting every candidate on one ballot.

Why do parties prefer closed primaries to open primaries?

Parties prefer closed primaries because they keep the choice of nominee in the hands of party members. That protects the party's brand and its leadership's influence, and it shields incumbents from voters who are not loyal to the party. IVP argues this is a private interest that should not control a public election.

The Constitution protects a party's right to keep non-members out of its own affairs. IVP's answer, made in Rieckhoff v. Berger, is that it equally protects a voter's right not to join, and that a state cannot make joining a party the price of a ballot it pays for.

Pros and cons at a glance

Pros

Every taxpaying voter can vote in a publicly funded election.
Independents get a say in the round that decides most safe-seat races.
Candidates must appeal to the whole electorate, not just the party base.
Voters are not forced to publicly declare a party to receive a ballot.

Cons

Parties lose sole control over who becomes their nominee.
In party-ballot open primaries, members of one party can cross over.
Ballots can grow long when every candidate appears together.
Rules differ across offices, which can confuse voters.

Does crossover voting, or party raiding, happen?

It is the most common objection. In a party-ballot open primary, a voter from one party could in theory pick the other party's ballot to boost a weak candidate. A nonpartisan open primary removes the incentive, because there is no separate party ballot to raid: everyone votes on the same list of candidates and the top finishers advance.

“Taxpayer-funded elections should serve the public, not private political parties.”

Independent Voter Project, guiding principle

Which version does IVP support?

IVP supports nonpartisan open primaries because they answer the strongest cons while keeping every pro. It wrote Proposition 14, California's Top-Two, which voters passed in 2010 and which survived two federal legal challenges. Nearly 40 million Californians now vote in a primary that does not require party membership.

Compare every system on the open vs closed primaries page, or return to the open primaries overview.

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Common questions

What are the pros and cons of open primaries?: Supporters say open primaries give every taxpayer a vote in publicly funded elections, push candidates to appeal beyond their base, and bring independents into the round that decides most races. Critics say they weaken party control over nominees and may invite crossover voting. Nonpartisan top-two designs answer the crossover concern with one shared ballot.
Why do parties prefer closed primaries to open primaries?: Closed primaries let parties limit nominee selection to their own registered members, which gives party insiders and the most active base voters more influence. Parties also argue they have a constitutional right of association to exclude non-members. IVP answers that voters have an equal right not to join, and the state should not make joining the price of a ballot.
Do open primaries let the other party sabotage a primary?: That concern, often called party raiding, is one of the most common arguments for closed primaries. Nonpartisan top-two systems are designed to sidestep it, because there are no separate party primaries to raid. Every voter receives the same ballot listing every candidate, and the top finishers advance regardless of party.
Which is better, open or closed primaries?: The Independent Voter Project holds that open, nonpartisan primaries are better for voters because they give every taxpayer an equal vote in a publicly funded election. Closed primaries suit people who want party members alone to pick nominees. For the 63 million voters registered as independent or unaffiliated, only open systems guarantee a voice in the deciding round.
Why do primary elections matter so much?: In many districts the primary is the election that actually decides who wins. Ballotpedia found that only 22.1% of possible 2026 primaries were contested, and MultiState reports that 32.5% of state legislative general election seats are on track to be uncontested by one major party in 2026. Where one party dominates, the primary is the real contest.

Read all 43 questions in the open primaries FAQ

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