Primaries and Caucuses

For most of the nineteenth century, party leaders chose nominees at conventions. Progressive reformers championed the direct primary, in which voters choose a party's nominee, and Wisconsin enacted the first statewide primary law in 1903. Primaries spread for state and congressional offices, but presidential nominations remained largely in the hands of party leaders until the turbulent 1968 Democratic convention, after which the McGovern-Fraser Commission rewrote the rules so that most delegates are chosen through primaries and caucuses, and Republicans followed.

Primaries are run by state governments and come in several forms: closed primaries limited to registered party members, open primaries in which any voter may choose a party's ballot, and semi-open versions. California and Washington use a top-two primary in which all candidates appear on one ballot regardless of party, and Alaska uses a top-four primary followed by ranked-choice voting in the general election. Caucuses are party-run meetings where participants gather to discuss and vote, and have become less common. Presidential delegates are allocated proportionally in Democratic contests and by a mix of proportional and winner-take-all rules in Republican contests.

The calendar is a constant source of controversy. Iowa's caucuses led off the presidential contest from 1972, followed by the New Hampshire primary, but Democrats moved South Carolina to the front in 2024 after problems with the 2020 Iowa count. Critics say primaries reward ideological candidates because turnout is low and dominated by the most engaged partisans, and that early states have outsized influence, while supporters say primaries give voters rather than party bosses the power to choose nominees. Reformers have proposed nonpartisan or ranked-choice primaries, which have passed in some states and been rejected in others.