Primary elections or primaries are elections held to determine which candidates will run in an upcoming general election. In a partisan primary, a political party selects a candidate. Depending on the state or party, there may be an "open primary", in which all voters are eligible to participate, or a "closed primary", in which only members of a political party can vote. Less common are nonpartisan primaries in which all candidates run regardless of party.

The origins of primary elections can be traced to the progressive movement in the United States, which aimed to take the power of candidate nomination from party leaders to the people. However, political parties control the method of nomination of candidates for office in the name of the party. Other methods of selecting candidates include caucuses, internal selection by a party body such as a convention or party congress, direct nomination by the party leader, and nomination meetings.

A similar procedure for selecting individual candidates under party-list proportional representation can be found in open list systems; in such systems, the vote for deciding which candidates on the list enter the legislature is combined with the general election (but the party itself may nonetheless hold a primary to decide which candidates are named on the list in the first place). Parties in countries using the parliamentary system may also hold leadership elections. A party's leader will typically become the head of government should that party win a majority of seats in the legislature (either in its own right or through a coalition with other parties), meaning leadership elections often select a party's de facto candidate for prime minister, much like a presidential primary. An electoral alliance, which is composed of multiple parties each with its own separate leader and organs, may also hold a common prime ministerial primary as in the 2021 Hungarian opposition primary, or a single party may wish to retain its leader but select someone else as its prime ministerial candidate, as the Portuguese Socialist Party has done in 2014.

Countries that use first-past-the-post for both the primary and general elections are often described as using a partisan two-round system to highlight the similarity to two-round (runoff) systems, particularly in two-party systems. These similarities have led to the first round of a two-round system sometimes being called a "nonpartisan primary" in the United States.

Types of party primaries

Two types of party primaries can generally be distinguished:

Closed primary. (synonyms: internal primaries, party primaries) In the case of closed primaries, internal primaries, or party primaries, only party members can vote. Open primary. All voters can take part in an open primary and may cast votes on a ballot of any party. The party may require them to express their support to the party's values and pay a small contribution to the costs of the primary.

In the United States, further types can be differentiated:

Closed primary In a "closed primary", people may vote in a party's primary only if they are registered members of that party prior to election day. Independents cannot participate. Because some political parties name themselves independent, the terms "non-partisan" or "unaffiliated" often replace "independent" when referring to those who are not affiliated with a political party. As of 2026, thirteen states require elections to have closed primaries while in 4 states both parties voluntary use closed primaries, and in 6 states only the Republican party uses closed primaries.

Semi-closed or semi-open In a "semi-closed primary", as in closed primaries, registered party members can vote only in their own party's primary. Semi-closed systems, however, allow unaffiliated voters to choose a party to participate in as well. Depending on the state, independents either make their choice of party primary privately, inside the voting booth, or publicly, by registering with any party on Election Day.

Sixteen statesAlaska, Arizona, California, Colorado, Illinois, Iowa, Kansas, Maine, New Hampshire, New Jersey, North Carolina, Ohio, Oregon, Rhode Island, Utah, and West Virginiahave semi-closed primaries that allow voters to register or change party preference on election day. Massachusetts allows unenrolled voters or members of minor parties to vote in the primary of either major party, but registration or party changes must be done no fewer than 20 days prior to the primary.

Open primary In an "open primary", a registered voter may vote in any party primary regardless of his or her own party affiliation. Fourteen statesAlabama, Arkansas, Georgia, Hawaii, Michigan, Minnesota, Missouri, Montana, North Dakota, South Carolina, Texas, Vermont, Virginia, and Wisconsinhave open primaries.

This system is sometimes criticized for increasing the ease with which voters can engage in party raiding. Raiding consists of voters of one party crossing over and voting in the primary of another party, effectively allowing a party to choose a weak opponent in the election. An example of this can be seen in the 1998 Vermont senatorial primary with the nomination of Fred Tuttle as the Republican candidate in the general election.

Nonpartisan

Nonpartisan blanket primary

In a "nonpartisan blanket primary", all candidates appear on the same ballot and advance to the general election or second round regardless of party affiliation. In the "top-two primary" variant, the top two candidates advance to the general election or runoff. Louisiana has famously operated under this system, which has been nicknamed the "jungle primary", since the 1980s. California has used a top two primary outside of presidential elections since 2012 after passing Proposition 14 in 2010. Washington has used a top-two primary since 2008.

Unified primary

In a "unified primary" (also known as a "top-two approval primary"), all candidates appear on the same ballot (similar to the nonpartisan blanket primary). However, unlike the kinds of primaries mentioned above, in a "unified primary" uses a nonpartisan primary with approval voting, where voters may support any number of candidates instead of one. St. Louis, Missouri uses this system.

In the United States

The United States is one of a handful of countries to select candidates through popular vote in a primary election system; most other countries rely on party leaders or party members to select candidates, as was previously the case in the U.S.

The selection of candidates for federal, state, and local general elections takes place in primary elections organized by the public administration for the general voting public to participate in for the purpose of nominating the respective parties' official candidates; state voters start the electoral process for governors and legislators through the primary process, as well as for many local officials from city councilors to county commissioners. The candidate who moves from the primary to be successful in the general election takes public office.

In modern politics, primary elections have been described as a vehicle for transferring decision-making from political insiders to voters, though political science research indicates that the formal party organizations retain significant influence over nomination outcomes.Cohen, Marty. The Party Decides: Presidential Nominations Before and after Reform. Chicago: University of Chicago, 2008.

Studies have found little-to-no difference between top-two and traditional partisan primaries on most outcomes like political polarization, but lower levels of electoral participation and more voter confusion under nonpartisan primaries.

History The direct primary became important in the United States at the state level starting in the 1890s and at the local level in the 1900s.Alan Ware, The American direct primary: party institutionalization and transformation in the North (Cambridge UP, 2002). The first primary elections came in the Democratic Party in the South in the 1890s starting in Louisiana in 1892. By 1897 the Democratic party held primaries to select candidates in 11 Southern and border states. Unlike the final election run by government officials, primaries were run by party officials rather than being considered official elections, allowing them to exclude African American voters. The US Supreme Court would later declare such white primaries unconstitutional in Smith v. Allwright in 1944.Michael J. Klarman, "The White Primary Rulings: A Case Study in the Consequences of Supreme Court Decisionmaking". Florida State University Law Review (2001). 29#1: 55–107 online.

The direct primary was promoted primarily by regular party leaders as a way to promote party loyalty.Ware, 2003. Progressive reformers like Robert M. La Follette of Wisconsin also campaigned for primaries, leading Wisconsin to approve them in a 1904 referendum.Robert C. Nesbit, Wisconsin: A History (1973) 412-415.Irvine L. Lenroot, Wisconsin Magazine of History 26#2 (1942), pp. 219–21. online

Despite this, presidential nominations depended chiefly on party conventions until 1972. In 1968, Hubert Humphrey won the Democratic nomination without entering any of the 14 state primaries, causing substantial controversy at the national convention. To prevent a recurrence, Democrats set up the McGovern–Fraser Commission which required all states to hold primaries, and the Republican party soon followed suit.Karen M. Kaufmann, et al., "A Promise Fulfilled? Open Primaries and Representation," Journal of Politics 65#2 (2003): 457-476. online

Non-partisan Primaries can be used in nonpartisan elections to reduce the set of candidates that go on to the general election (qualifying primary). (In the U.S., many city, county and school board elections are non-partisan, although often the political affiliations of candidates are commonly known.) In some states and localities, candidates receiving more than 50% of the vote in the primary are automatically elected, without having to run again in the general election. In other states, the primary can narrow the number of candidates advancing to the general election to the top two, while in other states and localities, twice as many candidates as can win in the general election may advance from the primary.

Blanket When a qualifying primary is applied to a partisan election, it becomes what is generally known as a blanket or Louisiana primary: typically, if no candidate wins a majority in the primary, the two candidates receiving the highest pluralities, regardless of party affiliation, go on to a general election that is in effect a run-off. This often has the effect of eliminating minor parties from the general election, and frequently the general election becomes a single-party election. Unlike a plurality voting system, a run-off system meets the Condorcet loser criterion in that the candidate that ultimately wins would not have been beaten in a two-way race with every one of the other candidates.