Step by step: How the Iowa caucuses work, and why there could be more than one winner

Your guide to what could be caucus chaos. 😱

Residents are stopped at the door after arriving moments after the 7:00 p.m. cutoff time at the community center on Monday.Andy Abeyta/Associated Press

For well over a year, as many as 25 Democrats have run for president all over the country. Nearly all came to the same conclusion: Iowa or bust.

Senator Kamala Harris of California decided she was all in on the Hawkeye State, ditching New Hampshire and colorfully telling a colleague, “I’m [expletive] moving to Iowa!”

She has since dropped out of the race. But the political stakes of doing well in Iowa remain just as high as ever. Former vice president Joe Biden could see his electability argument pierced if he loses badly in Iowa. Former mayor Pete Buttigieg of South Bend, Ind., and Senator Amy Klobuchar of Minnesota might see their campaigns take off or wither, depending on what happens in Iowa. If Senator Bernie Sanders or Senator Elizabeth Warren find a way to win in Iowa, they may easily win New Hampshire and be handed the nomination.

But here’s an ugly twist: For the first time in history, caucus night could end with three people who can say, without spin, that they won Iowa.

If that happens, what did all of that attention on Iowa really even mean?

To find out how that could happen, let’s dive into how the caucuses are set to work on Monday.

1. A caucus is not a primary

No voting booths. No bubbles to fill in. No hanging chads.

Allison Berryhill, precinct chair for Audubon County Precinct 2, display a form used by caucus-goers to fill out their first choice for Democratic presidential nominee. Jessica Rinaldi/Globe Staff

It’s a caucus, not a primary. And for the grammarians out there, let’s begin with one technical point of clarification: it is not accurate to call it the Iowa caucus. It is the Iowa caucuses. That is because on Monday night at 8 p.m. Eastern, voters in Iowa will head to one of 1,678 locations. These locations are usually a school gym or a community center. But the caucus is technically a party activity and not sanctioned by the state, and some small towns pick a church or even someone’s home.

When people show up, they don’t just sign in and head to a voting booth. No, they settle in and get ready to stick around for an hour or more. Anyone can show up to the Democratic caucuses — even Republicans. These meetings are, at heart, a party building activity. But whoever shows up must declare themselves a member of the party.

2. The initial organization

After some explanation of the rules and procedure — and, depending on the precinct, sometimes speeches on behalf of each candidate — those in the room can announce candidates they like and then the chair of the meeting will suggest that anyone who likes that person all clump together in some spot in the room.

Again, there isn’t a ballot. If someone wanted to suggest that Michelle Obama should be the next president, then folks can join that circle, even though Michelle Obama is not running for president.

In addition — and this is important — those in the meeting can also decide to remain “uncommitted.” (Fun fact: uncommitted, not Jimmy Carter, won the 1976 Iowa Democratic caucuses.)

3. The first count

Once people are either clustered behind a candidate or in the uncommitted camp, there will be a head count of how many people are in the room and how many people are in each group. For the first time ever, this number will be written down and submitted to the state party. (More on that later.) Then all that matters is whether each candidate has at least 15 percent and is thus considered “viable.”

4. The reorganization

The caucus chair will announce that certain candidates have not met viability. For example, no candidate outside of Biden, Sanders, Buttigieg, and Warren has consistently polled above 15 percent. At this point, ONLY those who are with a non-viable candidate or uncommitted can then choose to go to a new group backing a different candidate. This is new. In previous years, even those with a front-runner could move to help another candidate or just change their minds on a whim. The reason for the change: speed.

5. And on and on

Then one or more rounds like this can continue until either everyone is aligned with a group that is viable or the caucus chair comes to the determination that those who are uncommitted prefer to stay that way.

6. So how could there be three winners?

In the past, Iowa Democrats have only declared a winner based on the percentage of delegates that candidate would eventually send to the state convention. But in 2016, Hillary Clinton barely beat Sanders in the delegate count. The Sanders campaign contended they actually had more supporters on caucus night, but because of quirks in how delegates are allocated, they lost the delegate game. Since no one actually recorded a pure head count, there was no way to know for sure if Sanders was right.

So this year, Iowa Democrats will report a) the number of people in each group initially b) the number of people in each group at the end and c) the percentage of delegates each candidate would receive at the state convention.

The Associated Press announced it will report all three numbers, but consider the delegate winner to be the actual winner.

However, with a field this large and a race this unsettled, there could be two or even three winners — one from each count.

That could make for chaos.

When George H.W. Bush won the 1980 Iowa Republican caucuses, he came to New Hampshire declaring that he had “the big mo” — momentum. Indeed, research has shown that the winner of the Iowa caucuses immediately can see a large uptick in poll numbers in New Hampshire.

But if three winners emerge from the Iowa caucuses on Monday, more than a year of campaigning could leave the top candidates with no more “mo” than they had the day before.