DES MOINES, Iowa (AP) -- All across Iowa next Tuesday, tens of thousands of Republican voters will travel through a chilly Midwestern night to the warmth of a local church or gymnasium for caucus meetings to select presidential candidates, the first voting in the 2012 election campaign.
These Midwestern, mostly white voters hardly resemble America as a whole, and their voting system puzzles most people. Yet Iowa holds substantial sway over how the nation chooses the president.
"Iowa will choose the next president of the United States in their early caucuses," Republican hopeful Michele Bachmann said recently. "This is the cannon shot."
The caucuses - essentially community meetings - have served as a launching pad to the nomination, and often to the White House, for the past 40 years, though they've been around since the 1840s. Candidates tend to lavish attention on Iowa, hoping that a good showing will give them a burst of publicity to improve their chances in New Hampshire, which votes Jan. 10, and in other early voting states.
It's this contest that helped propel Republican George W. Bush and Democrat Al Gore to their parties' nominations in 2000. It also helped Democrat John Kerry become Bush's challenger in 2004. And the caucuses gave Democrat Barack Obama his first win in 2008, though Mike Huckabee won on the Republican side, not the eventual GOP nominee, John McCain.
The caucus process seems arcane and mysterious, even to people in Iowa. That is in part because most people don't even participate. About 359,000 people - 17 percent of registered voters in Iowa - showed up for Democratic and Republican caucuses in 2008. Turnout will certainly be lower this year, since Obama is unopposed. And the GOP turnout may not exceed the record-setting 120,000 attendees that the party's contest saw four years ago.
Caucuses are held in all of the state's 1,774 voting precincts, some in remote spots where only a handful of voters gather, others in big community centers or schools that host several precincts under one roof. In all, Republicans will gather in about 800 locations.
This relatively small number of voters, and their overwhelmingly white makeup, routinely bring Iowa's caucuses under attack by outsiders who want more clout for their own states. Only 5 percent of Iowa's electorate is Hispanic and only 3 percent is black, compared with a national electorate that is 16 percent Hispanic and 12 percent black.
For their part, Iowans jealously guard their first-in-the-nation nominating contests.
While both parties in Iowa use the caucus system to choose candidates, Republicans and Democrats go about things differently.
For the GOP, the caucuses are simply a straw poll, meaning the results are not binding. While Democrats use the caucuses to choose delegates who are expected to support their favored candidate, Republicans handle that later at county and district conventions.
After electing a temporary chair to run the meeting and a secretary to record the proceedings, any Republican who chooses can briefly speak in favor of a candidate. Ballots are then passed out and participants mark their choices in private. Those ballots are quickly counted and the results called into party headquarters, where they are posted online as they are received.
Any Republican voter can participate, including those who register when they arrive at the event. People too young to vote can also take part if they will be 18 by the general election.
Democrats, when there are multiple candidates, take a more convoluted approach.
Democrats break into preference groups at their caucuses, publicly declaring which candidate they favor. Candidates must get support from 15 percent of those attending the caucus in order to receive votes. Once they break into those groups, activists try to attract those whose candidates have fallen short of the 15 percent threshold.
After the results are reported to party headquarters, the numbers are run through a formula that changes the value of votes based on a county-by-county analysis of Democratic performance in the last gubernatorial and presidential elections.
"The Republican caucuses and Democratic caucuses are two different beasts," said Democratic strategist Phil Roeder. "In the big picture, it makes for a very different result."
Democratic strategist Jerry Crawford put it another way: "Democrats always like to make things more difficult."
Although the Republicans have a simpler system, caucuses by both parties require more time and greater participation than in a primary election.
Activists said that level of commitment means that for a candidate to be successful, he or she must make connections with voters, then build an organization that can get them to their precinct gatherings.
"People still expect to see the candidates in person," said Steve Scheffler, who heads the influential Iowa Faith and Freedom Coalition. "The candidates who have spent the most time here will benefit."
Associated Press writer Libby Quaid in Washington contributed to this report.