State Primary Election Types

Last updated September 28, 2011

The manner in which party primary elections are conducted varies widely from state to state.  Most primaries can be categorized as either open, closed or top-two. In other states, the primary type does not fall neatly into a category, but may represent a hybrid of these types.

Open Primaries

Eleven states operate open primaries, which permit any registered voter to cast a vote in a primary, regardless of his or her political affiliation. This means that a Democrat could "cross over” and cast a vote in the Republican primary, or vice versa, and an unaffiliated voter can choose either major party's primary. 

Proponents say that this system gives voters maximum flexibility because they can cross party lines. Opponents counter that this system dilutes a political party’s ability to nominate its own candidate without interference from non-members.

Closed Primaries

Eleven states operate closed primary elections or caucuses. In either case, only voters who are registered as members of a political party prior to the primary date may participate in the nomination process for its candidates.

Proponents say that closed systems contribute to a strong party organization. Opponents note that independent or unaffiliated voters are excluded from the process.

Top-Two Primaries

In top-two primaries all candidates, regardless of party affiliation, are listed on one ballot. Voters choose their favorite candidate, and the top two vote-getters become the candidates in the general election.  The top-two model is not used for presidential primaries in any state.  In Nebraska, it is used only for the state's nonpartisan legislature and for some statewide races.  In California, Louisiana and Washington, the top-two primary is used for state and Congressional races.

Proponents say that top-two primaries give independent voters an equal voice and may help elect more moderate candidates from the major parties. Opponents argue that it can reduce ballot access for third party candidates and lessen voter choice in that two Democrats or two Republicans could be the only candidates in the general election. 

Hybrid

Many states use primary election systems that fall somewhere in between "open" and "closed."  Procedures are unique from state to state, and how to categorize these primaries is a judgment call.  Some states allow voters to cross party lines to vote.  Depending on the state, choosing a ballot may actually be a form of registration in the party.  States in this category also vary according to how they treat unaffiliated voters. They may or may not be permitted to vote in party primaries.  In some states, such as Alaska, political parties may decide for themselves whether to permit voters who are unaffiliated or are members of another party to participate in their primary.  The parties may not necessarily all choose the same approach in a given state.  For instance, in 2008 and 2010, the Alaska Democratic party allowed any registered voter, regardless of party affiliation, to participate in its primary, while the Republican party limited participation in its primary to its own members.

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Contact NCSL's elections team at 303-364-7700.