The nuts and bolts of the Iowa caucuses

Unlike traditional primaries, in which voters have a 14-hour window to show up at the polls, caucus-goers in Iowa will report to their precinct meetings tonight at 7 p.m., sharp.

“You have to commit to being there for a couple of hours,” said Dennis Goldford, professor of political science at Drake University in Des Moines. “You have to hope there’s no blizzard, the car starts, and the babysitter shows up. So, in that sense, it can be difficult to predict who will actually show up for caucuses.”

Local Republican and Democratic parties will hold 1,681 caucus meetings at schools, churches, and libraries. Republican candidates are vying for Iowa’s 30 delegates at this summer’s national convention—out of 2,472 total. Democrats get 44 convention delegates from Iowa, out of 4,051.

Most Republican caucuses select their winner by a simple show of hands or secret ballot. On the Democratic side, caucus-goers stand together in “preference groups.” If a candidate’s group is too small, supporters have to choose another, more viable candidate. Both parties dole out delegates to candidates proportionally, so it’s not a winner-take-all system.

Though the Iowa caucuses dominate news as the first vote in the presidential primary race, within Iowa, turnout at the meetings often is underwhelming.

“For all the attention to the Iowa caucuses, on average only 1-in-5 eligible members of each party actually participates in the caucuses. Most people don’t. So it’s the hardest-core activists,” Goldford said.

On the Republican side, pre-caucus polls suggest Sen. Ted Cruz, R-Texas, has the most support among voters who describe themselves as “very conservative.” Most of Donald Trump’s support comes from moderates. Much of the outcome depends on who shows up tonight.

Goldford said the Iowa caucuses make the candidates spend time in face-to-face contact with voters all across the state, something far more difficult to do in most of the states that vote later.

“Iowa forces candidates to treat individual voters as real human beings,” Goldford said. “In other words, these candidates have to talk to everyday people, they can’t just treat them like campaign props.” After tonight’s outcome, it will be up to the losers to decide whether to stay in the race or stubbornly fight on to the New Hampshire primary next week.

“Iowa doesn’t determine who the nominee will be for either party,” Goldford said. “What Iowa tends to do is winnow the field.”

In the past five contested elections, the winner of Iowa’s Democratic caucus went on to become the party nominee three times. The Republican caucus winner in the past five contested elections turned out to be the nominee only twice: Bob Dole in 1996 and George W. Bush in 2000.

Listen to Joseph Slife’s report on the Iowa caucuses on The World and Everything in It.