In presidential elections, political parties nominate their candidates at national party conventions. Each state's party members are represented by a number of delegates who vote at the convention. Fifteen U.S. states and territories use caucuses to select delegates for each party's convention, and four others use a mix of caucus and primary election. Each election year, approximately 10 percent of Democratic and 15 percent of Republican delegates are chosen by caucuses.

An American Institution

From the early 1800s, caucuses became the preferred way for parties to select presidential candidates. Those early caucuses were only open to high-ranking or elected officials within the party, but by 1830 movements began to open these early contests to ordinary party members. For years, most states used caucuses to determine their choice for presidential candidate. However, following the 1968 election, Democrats pushed to make the selection process more open to everyday citizens. Although most caucuses were open, in practice only the party elite attended them. In ensuing years, the Democratic party in most states switched to a primary election system, where all party members voted privately by secret ballot. Republican parties followed suit.

Bucking the Trend

A few states, however, preferred the traditional caucus system to the more open primary election system. While states with primaries have higher levels of participation among registered voters than caucus states do, proponents of the caucus system argue this fulfills the U.S. Contstitution's intent. Retaining the caucus system rewards passionate activists and diehard party members willing to take part in the often time-consuming process of selecting a candidate. Unlike primaries, caucuses are public affairs that may last several hours as selected party members speak on behalf of their chosen candidate.

The Importance of Iowa

Iowa's caucus has long been seen as important, in part because it is the first presidential vote in the country. In the 1972 presidential race, a little-known Democratic candidate from Georgia committed to intense campaigning in the state and won the caucus by a decisive margin. Jimmy Carter was thrust into the national spotlight and used the momentum from the Iowa caucus to carry him through to the White House. Ever since, Iowa has been a key state to establish momentum and set national perceptions about candidates.

Mixed Caucus Systems

A few states have developed mixed systems that use both caucuses and primaries to decide which candidate will receive their votes. In some states, the Democratic party holds a primary while the Republican party has a caucus. Others use more complicated systems. In Arizona, for example, the Republican party holds a primary first, then selects delegates at a later caucus. The Texas Democratic party divides its national convention delegates using both systems: 30 percent of the delegates are chosen through a caucus and the remaining 70 percent come from primary election votes.