The caucus is generally defined as a "gathering of neighbors." Rather than going to polls and casting ballots, Iowans gather at a set location in each of Iowa's 1784 precincts. Typically, these meetings occur in schools, churches, or public libraries. The caucuses are held every two years, but the ones that receive national attention are the presidential preference caucuses held every four years. In addition to the voting, caucus attendees propose planks for their party's platform, select members of the county committees, and discuss issues important to their local organizations.
Participants indicate their support for a particular candidate by standing in a designated area of the caucus site (forming a "preference group"). An area may also be designated for undecided participants. Then, for roughly 30 minutes, participants try to convince their neighbors to support their candidates. Each preference group might informally deputize a few members to recruit supporters from the other groups and, in particular, from among those undecided. Undecided participants might visit each preference group to ask its members about their candidate.
After 30 minutes, the electioneering is temporarily halted and the supporters for each candidate are counted. At this point, the caucus officials determine which candidates are "viable". Depending on the number of county delegates to be elected, the "viability threshold" can be anywhere from 15% to 25% of attendees. For a candidate to receive any delegates from a particular precinct, he or she must have the support of at least the percentage of participants required by the viability threshold. Once viability is determined, participants have roughly another 30 minutes to "realign": the supporters of inviable candidates may find a viable candidate to support, join together with supporters of another inviable candidate to secure a delegate for one of the two, or choose to abstain. This "realignment" is a crucial distinction of caucuses in that (unlike a primary) being a voter's "second candidate of choice" can help a candidate.
When the voting is closed, a final head count is conducted, and each precinct apportions delegates to the county convention. These numbers are reported to the state party, which counts the total number of delegates for each candidate and reports the results to the media. Most of the participants go home, leaving a few to finish the business of the caucus: each preference group elects its delegates, and then the groups reconvene to elect local party officers and discuss the platform.
I know, it's a lot harder than showing up at the polls and casting a vote. But what makes it hard is also what makes it great. I have no problem with Iowa going first in the country because they don't just vote, they debate, they listen, they struggle to make a decision, and they don't do it in anonymity, they do it in front of their friends and neighbors. That's right, no secret ballots, you have to stand up and say "I support this candidate and here is why." This is the essence of Democracy, this is the will of the people being decided together, at the local level.
And you know what else I like about the caucuses? Morons don't usually take the time to participate. There, I said it. I hate the fact that idiots can decide who my nominees for President are going to be and in Iowa, it takes a truly motivated idiot to make that happen.
In fact, after seeing what happened during the last Presidential election, I think the whole damn country should be forced to caucus.
When George W. Bush gets re-elected, I just know that there were people voting for him who never would have had the guts to look their neighbor in the eye and defend their decision.
So, the next time you hear someone complain about the caucus system in Iowa, take it with a grain of salt. In fact, tell'em to really look into the facts. It might be harder to participate, but the quality of the participation more than makes up for it.
And nothing makes a person do their homework like having to defend their position in public. That is why Iowa should go first in the country and that is why they should continue to caucus, because by the time these guys leave Iowa, the world has a pretty good idea who they are.
If you want more information on the Iowa caucuses, here are a few decent links.