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Types of Primary Systems, Explained

What are the primary rules in your state?

Carlo Macomber
Research Manager
October 31, 2023

Partisan primaries are the biggest, most solvable problem in American politics today. The “Primary Problem” disenfranchises voters, elects leaders who don’t represent the majority, and ultimately helps explain why Congress is incapable of solving our country’s biggest problems.

In order to fix the Primary Problem, we need to replace partisan primaries with nonpartisan alternatives. Currently, 46 states use some kind of partisan primary, while four use nonpartisan primaries.

Here are the types of primary systems, explained.

Partisan Primaries

All 50 states hold primary elections for federal and state offices to determine which candidates appear on the general election ballot. The vast majority of states (46) use a partisan primary for congressional offices. In a partisan primary, eligible voters cast ballots to select the party’s official nominee for the general election. 

While partisan primary rules differ slightly in these 46 states, there are three broad categories: closed, semi-open, and open. In all three categories, the Republicans and Democrats have separate primary ballots. This means that voters cannot vote for a Republican for one contest, and a Democrat in another, even if those candidates best represent their views.

  • 15 states have closed partisan primaries for congressional offices and state offices. In these states, only registered party members have a guaranteed right to vote in partisan primaries. Independent voters are barred from participating in primaries unless the parties establish a rule allowing them to participate. No state Republican Party in these sixteen states allows independents to participate in their primaries, while just five state Democratic parties do so (ID, NE, OK, SD, UT).
  • 16 states have semi-open partisan primaries for congressional offices and 15 do so for state offices.1 Under this system, independent voters have a guaranteed right to participate in the primary of their choice. However, registered partisans are only able to vote in their party’s primary.
  • 15 states have open partisan primaries for congressional and state offices. The Democratic and Republican parties still hold separate primary elections, but all registered voters, regardless of party, can choose which party’s primary they would like to participate in. This system gives voters the most flexibility among partisan primary systems.

There is even more variation within these categories. For example, some closed primary states allow voters to register with a party — and therefore participate in its primary — on the day of the primary election. Others require voters to be registered with the party by a set deadline prior to primary day. However, all closed primary states share one thing in common: Voters must become members of the party in order to participate in its primary. For that reason, they are grouped together.

Nonpartisan Primaries 

The remaining four states (Alaska, California, Louisiana, and Washington) hold nonpartisan primaries. In nonpartisan primary systems, all candidates, regardless of party, appear on one ballot, and all registered voters are eligible to participate. The top vote getters advance to the general election. Unlike partisan primaries, the goal of a nonpartisan primary is not to select the official nominees of political parties. Rather, the nonpartisan primary serves as a winnowing election to ensure that a manageable number of viable candidates appear on the general election ballot. There are two main types of nonpartisan primaries in use today: Top Two and Top Four.

  • California and Washington hold top-two nonpartisan primaries for state and congressional offices. All candidates run on one ballot (with their party labels), and voters select their preferred candidate. The top two finishers, regardless of party, advance to the general election where a majority winner is guaranteed.2
  • Louisiana uses a slightly different variant of Top Two. Technically, the state does not hold primary elections, and all candidates run together in the general election. If one candidate receives a majority of votes cast, they are elected. If no candidate does so, the top two finishers advance to a runoff election held approximately five weeks later.
  • Alaska holds top-four nonpartisan primaries for state and congressional offices. Like Top Two, all candidates run on one ballot (with party labels), and voters select their preferred candidate. Unlike Top Two, the top four finishers advance to the general election. In the general election, voters rank the candidates, and, if needed, an instant runoff is held to ensure a majority winner.

Nonpartisan primaries ensure that all eligible voters have the freedom to participate in every taxpayer-funded election, and guarantee that the winner secures a majority of the vote. In practice, nonpartisan primaries give voters more voice, better choices, and better representation.

1 Nebraska uses a partisan primary system for congressional and statewide offices but a nonpartisan primary system for its unicameral state legislature.

2 Nebraska uses Top Two for its state legislative contests; however, party labels are not listed on the ballot.