The electoral process to nominate a candidate for a presidential election is usually called "the primaries," but there are two different systems that states use: caucus and primary.

Unlike a primary, where residents simply cast their ballots, a caucus is a local gathering where voters openly decide which candidate to support. The caucus format favors candidates who have a dedicated and organized following because a small band of devoted volunteers can exert an outsized influence in the open setting of a caucus.

States choose whether they want to hold primaries or caucuses. Most states hold primaries but states like Iowa, Louisiana, Minnesota and Maine use the caucus system.

Comparison chart

Caucus versus Primary comparison chart
Edit this comparison chartCaucusPrimary
Who can vote Only members registered with the political party can participate (if closed system) Depends upon the state. Some states allow only registered party members to vote; some allow party registrations on the same day; some are completely open to all residents of the state.
Voting method Voting is conducted at local party meetings and is done by raising hands or breaking up into groups. An election is held/ secret ballot
States States that use the caucus system are Alaska, Colorado, Hawaii, Kansas, Maine, Minnesota, Nevada, North Dakota, Wyoming and Iowa All other states

The Process

Voting in a primary or caucus

At a caucus, members of a political party meet in person at an appointed time and location to discuss the candidates and debate their merits. The voting for candidates happens either by raising hands or by separating into groups, with the votes being counted manually by counting the number of supporters of each candidate.

In contrast, a primary is much like a regular election i.e. depending upon the type of primary, those eligible to vote cast a secret ballot.

The caucus system was the original way in which political parties chose candidates. However, people began to feel that the secret ballot was a fairer, more democratic system so in the beginning of the 20th century, states began to move to the primary system.


At the heart of the electoral process is the system of delegates. Each state has a certain number of delegates that represent the state at the National Convention of either political party (Democrat or Republican). It is at this event that the party's presidential nominee is chosen.

The delegates of each state are "awarded" to one of the presidential candidates and the candidate with the most number of delegates on his/her side wins the nomination. Some states use a winner-take-all approach and award all their delegates to the winner of the caucus or primary in that state. Some states award delegates in proportion to the percentage of votes the candidates receive.

In general, states decide whether to hold a primary or caucus and this decision applies to both parties. But in some cases (for example, Washington) there are variances between the process used by Republican and Democratic parties in the same state.

Another difference is that there are some delegates (called unpledged delegates in the Republican system and superdelegates in the Democratic system) who are not bound by the results of the caucus or primary in their state. They are free to vote for the candidate of their choosing.

Types of Primaries

Iowa Caucus and New Hampshire Primary

The Primaries—the process of choosing a nominee, whether via a caucus or primary— begin with the Iowa caucuses; they are the first state to hold a caucus. New Hampshire is typically the second. Over the years, states have tried to move up the date on which they hold the caucus/primary in order to exert an outsize influence on the nominee selection. Candidates who win in early states gain momentum and credibility—both with voters in other states as well as wealthy donors—and for some candidates, a good showing in the early states may even prove their viability. For example, many regard Barack Obama's victory in the 2008 Iowa caucus as the turning point after which Hillary Clinton was no longer considered the inevitable Democratic choice.

On the flip side, Republican caucus-goers in Iowa chose Rick Santorum in 2012 and Mike Huckabee in 2008, both candidates who eventually went on to lose the battle for nomination. Similarly, Jon Huntsman and Rick Santorum were placed #1 and #2 respectively in the 2008 New Hampshire primaries for the GOP; neither won the Republican nomination.

State by state information

State Type
Alabama Open Primary
Alaska Caucuses
Arizona Closed PPE
Arkansas Open Primary
California Primary
Colorado Caucuses
Connecticut Closed Primary
Delaware Closed Primary
District of Columbia Primary
Florida Closed Primary
Georgia Open Primary
Hawaii Open Caucuses
Idaho Open Primary
Illinois Semi-Open Primary
Indiana Open Primary
Iowa Caucuses
Kansas Caucuses
Kentucky Closed Primary
Louisiana Caucus
Maine Caucuses
Maryland Closed Primary
Massachusetts Semi-Closed Primary
Michigan Open Primary
Minnesota Open Caucuses
Mississippi Open Primary
Missouri Open Primary
Montana Open Primary
Nebraska Caucuses (Democratic); Primary (GOP)
Nevada Caucuses
New Hampshire Semi-Open Primary
New Jersey Primary
New Mexico Republican Primary; Democrat closed caucuses
New York Closed Primary
North Carolina Semi-Open Primary
North Dakota Open Caucuses
Ohio Semi-Open Primary
Oklahoma Closed Primary
Oregon Closed Primary
Pennsylvania Closed Primary
Rhode Island Primary
South Carolina Open Primary
South Dakota Closed Primary
Tennessee Open Primary
Texas Semi-Open Primary & Closed Caucuses
Utah Closed Primary
Vermont Open Primary
Virginia Open Primary
Washington Open Caucuses
West Virginia Closed Primary
Wisconsin Open Primary
Wyoming Caucuses


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"Caucus vs Primary." Diffen LLC, n.d. Web. 20 Feb 2019. < >