Iowans from all four corners of the state will caucus Monday, taking the first steps towards choosing presidential nominees and signaling the beginning of the end of more than a year of primary campaigning.

“If we win in Iowa, we go on to New Hampshire with momentum, we go onto Nevada, we go onto every state across the country, and Iowa is going to lead the way,” said Rep. Pramila Jayapal of Sen. Bernie Sanders’ campaign.

Every Democratic presidential candidate who has won the Iowa caucuses in the 21st century has gone on to win the party’s presidential nomination.

Iowa is the first electoral contest in the Democratic presidential nominating calendar, followed by New Hampshire, Nevada and South Carolina, with the ordering of the last two states flipped on the Republican side. The Republican Party in Nevada and South Carolina canceled their caucuses and primaries, respectively, in solidarity with President Donald Trump.

Who can participate?

Any resident of Iowa who is eligible to vote in the 2020 general election on Nov. 3, 2020, and registered with the party of the caucus they wish to participate in is eligible to take part in the caucuses. People must be at their caucus site before 7 p.m. in order to participate.

People who have not yet registered to vote or need to change their party may do so at their designated caucus sites. People can check their voter registration status on the Iowa Secretary of State’s website at https://sos.iowa.gov/elections/voterreg/regtovote/search.aspx.

In Ames, the Oakwood City Church is the only caucus site for Republican caucusgoers. Donald Trump Jr. is scheduled to speak on his father’s behalf at this caucus site, according to a press release.

A full list of Republican caucus sites across Iowa by precinct and a link to find which precinct people are registered to vote in is available on the Republican Party of Iowa’s website at https://www.iowagop.org/2020-caucus-locations/.

On the Democratic side, there are 20 caucus sites in Ames and 43 total across Story County. A full list of caucus sites is listed on the Story County auditor’s website at http://www.storycountyiowa.gov/1069/Caucus-Locations-2320.

Democratic caucusgoers can find their precinct caucus site at https://iwillvote.com.

How do the caucuses work?

On the Democratic side, the caucuses are more complex than simply voting.

People vote with their bodies, moving to a certain area of a room in an area with other supporters of their favored candidate. The number of votes a candidate receives factors into the number of delegates that candidate receives, with candidates needing to hit a 15 percent threshold in order to receive county delegates and state delegate equivalents.

If a Democratic caucusgoer’s favored candidate receives more than 15 percent support at a caucus site, their support is locked in, and they must sign what the party is calling a “presidential preference card” with the name of their candidate on it, and they can leave the caucus site.

If their candidate has fewer than 15 percent support, they will note the name of their first preference candidate on the card, and they must either join a candidate who had passed that threshold or try to convince other caucusgoers whose candidates were also non-viable to join their own group to reach 15 percent support. They will then note their final preference on the card, sign them and turn them in.

The Republican caucuses are closer to a traditional election, with the party conducting a “straw poll” and simply counting the number of votes each candidate receives. Delegates are awarded proportionally based on the number of votes a candidate receives.

Who is in the running?

It could be a very close result in the Democratic caucuses. On the Republican side, polls show a less close race.

The president leads his Republican rivals by as much as 86 percent in recent polling of likely Republican primary voters nationwide. He faces two rivals: former Gov. Bill Weld and former Rep. Joe Walsh.

Speaking in Cedar Rapids on Saturday, Sanders, one of the top contenders in polling of likely Iowa Democratic caucusgoers, said he believes if turnout is high, then he will win; if it is low, he will lose.

Democratic Iowa caucus polls have been close. The release of the highly anticipated “Iowa Poll” conducted by Selzer & Company for the Des Moines Register and CNN was canceled due to a potential “issue with the way the survey was administered, which could have compromised the results of the poll,” according to a column by Carol Hunter, the Register’s executive editor.

Though the Iowa Poll’s publication was canceled, there are plenty of other surveys that have been conducted providing an idea of where candidates stand. Sanders leads former Vice President Joe Biden by 23.8 percent to 20.2 percent in the RealClearPolitics polling average of likely Iowa Democratic caucusgoers as of Saturday.

Trailing in third place is former Mayor Pete Buttigieg with 15.6 percent, followed by Sen. Elizabeth Warren with 14.6 percent, Sen. Amy Klobuchar with 9.6 percent, businessman Andrew Yang with 3.8 percent and businessman Tom Steyer with 3.6 percent support. All other candidates, including Rep. Tulsi Gabbard, former Mayor Mike Bloomberg, Sen. Michael Bennet and former Gov. Deval Patrick, have fewer than 2 percent support among likely Iowa Democratic caucusgoers.

Polls all come with a margin of error, though. Former Secretary of State Hillary Clinton’s lead of four percent in the RealClearPolitics polling average over Sanders on the eve of the 2016 caucuses translated to the narrowest of wins on caucus night. She defeated Sanders by 0.2 percent, with the result not called until the following day.

When will the winner be known?

It depends on how close the margin is between the top candidates.

As was the case with Sanders and Clinton in 2016, it could be that the top candidates trade a lead of the state delegates awarded at each caucus site all night, and the final result may not be known until the next day or even later.

Then-Sen. Barack Obama was declared the winner of the 2008 Iowa caucuses before 8:30 p.m. in his nearly 8 percent win over second-place finisher John Edwards.

Though the Iowa Democratic Party will release preference totals for each round of the caucuses, in effect a popular vote total, the Daily will declare a winner in Iowa based on the number of state delegate equivalents each candidate wins, though all vote totals will be reported. This follows the lead of the Associated Press and the New York Times in declaring a victor.