
Republican presidential candidate former president Donald Trump arrives to speak at a commit to caucus rally, Jan. 6, 2024, in Clinton, Iowa. In 2024, Iowa will again hold the first Republican contest.Charlie Neibergall/The Associated Press
The U.S. presidential race officially gets underway on Jan. 15 with the Iowa caucuses, the first event on the 2024 election calendar and the start to a long primary season.
Iowa has served as the lead-off voting event since the 1970s, holding caucuses during which groups of registered voters meet to choose a presidential candidate. This year, the Democratic side has made some significant changes to the process, opting to solely focus on administrative business and using mail-in voting instead to select its nominee. The Republican process remains largely unchanged – and former president Donald Trump leads in the polls against an ever-shrinking field of candidates.
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Unlike in Canada, voters in the U.S. typically register as supporters of a political party when they sign up to vote. This allows them to take part in caucuses, and vote in primary elections, to choose a party’s nominee for president and other offices.
So, what are the Iowa caucuses? How do they differ from primaries? What are the key dates to note? Here’s what to know about the U.S. presidential primaries.
Who is running in the U.S. presidential primaries?

Former UN ambassador Nikki Haley, right and Florida Gov. Ron DeSantis, left, pointing at each other during the CNN Republican presidential debate in Des Moines, Iowa, Jan. 10, 2024.Andrew Harnik/The Associated Press
Joe Biden, the current sitting president, is running for re-election for the Democratic Party. The incumbent launched his re-election bid in April of last year, with a campaign video that opened with imagery from the Jan. 6, 2021 attack on the U.S. Capitol by supporters of former president Donald Trump.
Two other Democratic candidates are challenging Mr. Biden for the party’s presidential nomination: author Marianne Williamson and U.S. congressman Dean Phillips. Mr. Biden currently holds a comfortable lead in the polls.
Five Republican candidates are in the running for the party’s presidential nomination. Donald Trump leads the race by a considerable margin despite his indictments in four separate criminal cases. Former United Nations ambassador Nikki Haley and Florida Governor Ron DeSantis are battling for leading alternative, alongside entrepreneur Vivek Ramaswamy and former Arkansas governor Asa Hutchinson. Former New Jersey governor Chris Christie dropped out of the race on Jan. 10, but did not immediately endorse any of his rivals.
Several third-party hopefuls have also joined the fray, including independents Robert F. Kennedy Jr., Cornel West and Jill Stein.
What are the Iowa caucuses?
Iowa Caucus precinct workers count paper ballots after a Democratic presidential caucus at West Des Moines Christian Church in West Des Moines, Iowa, U.S., Feb. 3, 2020.JIM BOURG/Reuters
The Iowa caucuses are the first electoral test of the U.S. presidential race.
Instead of going to polling stations and casting ballots, voters gather on a midwinter evening – in church basements, school gymnasiums or living rooms – to debate and choose the person they want as their party’s presidential nominee.
Those who champion caucuses say they are the epitome of participatory democracy. You have a good discussion about politics with your fellow party members and think long and hard before making your choice. To detractors, they are an anachronism. The time commitment and inaccessibility leads to low voter turnout. Early or absentee voting is not permitted, except for a small handful of overseas and military votes the state party has allowed to be cast by mail.
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No matter whether you think they’re good or bad, the fact is the caucuses can make or break a presidential campaign. Post an unexpectedly good showing, and an upstart candidate can build enough momentum to pull ahead of the field; post a poor one and emerge wounded.
How are caucuses different from primaries?

Mail-in primary election ballots are processed at the Chester County Voter Services office in West Chester, Pa. on May 28, 2020.Matt Rourke/The Associated Press
In the United States, states that will use the caucus system in 2024 include Iowa, Nevada, Idaho, Missouri, North Dakota, Hawaii, Minnesota, Wyoming and Maine. U.S. territories American Samoa, Northern Mariana Islands Territory and the U.S. Virgin Islands also use caucuses.
One of the main differences between caucuses and primaries is the amount of time allotted for voting to occur and the methods by which people can vote.
Ahead of the Iowa and New Hampshire contests, a look at the literature of the two states
In a primary, people can show up at the polls and cast ballots throughout the day assigned by a state, from the early morning until polls close in the evening. They have the option of casting an absentee ballot if they can’t make it to the polls, and in some states, people may vote before the day the primary is held.
The Iowa caucuses, on the other hand, are held in the evening and voters must attend in person in order to participate, except in a few isolated instances. Caucuses are run by political parties, whereas primaries are usually (but not always) run by the state.
Are both the Republicans and Democrats holding caucuses in Iowa this year?
Democrats caucus at the University of Iowa Athletics Hall of Fame in Iowa City, Feb. 1, 2016.GABRIELLA DEMCZUK/The New York Times News Service
Sort of. While both the Iowa state Republican and Democratic parties will hold caucuses on Jan. 15, only the Republican event will have an immediate, binding impact on the presidential race.
In a departure from previous years, the Democratic caucuses will be held only to conduct administrative party business and to start the process of choosing delegates to the national conventions. Iowa Democrats will express their preferences for their party’s presidential nominee through a mail-in voting process, the results of which will not be known until March.
For Republicans, the Iowa caucuses will run as they always have. Voters taking part must arrive at their caucus site by 8 p.m. ET, at which point deliberations among caucus-goers begin behind closed doors. The length of the caucus meetings will vary from location to location, with most lasting about one hour to 90 minutes.
At the end of the meeting, voters in attendance cast a ballot for their preferred candidate, and those votes are tallied. Statewide caucus results will then be used to determine how many of Iowa’s 40 Republican National Convention delegates each candidate has won. Delegates are allocated to candidates in direct proportion to their share of the statewide vote.
Iowa makes up a minuscule share of the total number of Republican delegates nationwide (only 1.6 per cent). So, in theory, a candidate who performs poorly in Iowa has plenty of opportunities in the remaining states and territories to more than make up the difference.
Historically, how important are Iowa caucuses to the overall election?

Jimmy Carter, Democratic presidential candidate, left, speaks to a crowd of supporters on the Van Ryswyk farm in Des Moines, Iowa, Aug. 24, 1976. The once-every-four-years Iowa caucuses grew to be an entrenched part of U.S. politics, catapulting little-known one-time peanut farmer Carter's bid for the White House.The Associated Press
According to the state’s historical society, the caucuses go back as far as the mid-19th century, around the time Iowa joined the Union. But they only really gained importance in the 1970s.
Following the divisive 1968 Democratic convention, where Hubert Humphrey took the nomination despite having relatively little grassroots support, the party reformed its nominating process. The caucuses, which had previously consisted mostly of party insiders and activists, were now open to all registered Democrats. The Republicans adopted the same system in Iowa ahead of the 1976 election.
That year, on the Democratic side, a little-known former Georgia governor named Jimmy Carter realized he could use the new system to his advantage. He focused his attention on early-voting states, including a big push in Iowa. Mr. Carter placed second here (after “uncommitted” voters) and got the momentum he needed to overtake higher-profile candidates and ultimately reach the White House.
David Yepsen, former chief political reporter at the Des Moines Register, watched as attention on the Iowa caucuses built in the years that followed. “I went to a Carter news conference once and I was the only reporter who showed up,” he told The Globe and Mail in an interview from 2016. “I’ve seen these go from a handful of enthusiasts meeting with candidates in living rooms to huge events.”
Now, candidates often start campaigning in Iowa more than two years before the vote, staging hundreds of events across the state, flying in armies of staffers and saturating local television and radio with ads. The national and international media descend on Iowa too – the Des Moines Register estimated this year’s media pack will include 1,600 reporters and camera crews – turning the state into a temporary extension of Washington.
Who can vote in a presidential primary? How do primaries work?
Iowa caucuses:
For the Iowa caucuses, only Iowa residents who are registered Republicans and will be 18 years old by the November general election may participate in the GOP caucuses. However, Iowans who are not registered to vote or are registered with another political party may still participate in the caucuses if they register or change their party affiliation on caucus day at their precinct caucus location. Voters may only participate in the caucus in their home precinct and must be there in person.
Caucus-goers must attend their precinct caucus meeting in person to vote for a presidential nominee. Early or absentee voting is not permitted, except for a small handful of overseas and military votes the state party has allowed to be cast by mail.
Primaries:
Presidential primaries vary by state, but are often held in polling stations. There are two main types of primaries – closed or open – that determine who is eligible to vote. In a closed primary, voters may only vote in the primary of the party they are registered with. For example, a voter registered as a Republican can only vote in a Republican primary. In an open primary, however, people can vote for a candidate of any political party.
What are the next key events in the U.S. presidential election?

President Joe Biden speaks at a campaign event at Montgomery County Community College in Blue Bell, Pa., on Jan. 5, 2024.Stephanie Scarbrough/The Associated Press
After the Iowa caucus, New Hampshire will hold its primary, a contest run by state and local governments where participants vote for their preferred candidate in a secret ballot.
Here is a look at the timeline of events from now until election day on Nov. 5.
Jan. 15:
Iowa caucuses are held.
Jan. 23:
New Hampshire will hold its first-in-the-nation primary.
Jan. 31:
Federal Election Commission 2023 year-end filing deadline for candidates to declare the money they have raised and spent.
Feb. 3-June 4:
All other state’s primaries and caucuses will take place between February 3 and June 4.
March 5:
Known as Super Tuesday, this is the biggest single day of primaries and often helps whittle down the field of candidates. Both parties hold them in Alabama, Arkansas, California, Colorado, Maine, Massachusetts, Minnesota, North Carolina, Oklahoma, Tennessee, Texas, Vermont and Virginia. Democrats in Utah will also vote in their primary while Republicans hold their caucuses in the state. Republicans in Alaska vote in their primary.
June 4
The final states to hold their presidential primaries are scheduled to do so on this date. Some states have yet to set their primary or caucus dates.
July 15-18:
Republican National Convention in Milwaukee, Wisconsin, where the party formally chooses its candidate.
Aug. 19-22:
Democratic National Convention in Chicago, where the party formally chooses its candidate.
Sept. 16:
The date set by the Commission on Presidential Debates for the first presidential debate to take place. It will be held at Texas State University in San Marcos, Texas.
Sept. 25:
The date set for the only vice-presidential debate, to be held at Lafayette College in Easton, Pennsylvania.
Oct. 1:
The date set for the second presidential debate, to be held at Virginia State University in Petersburg, Virginia.
Oct. 9:
The date set for the third and final presidential debate, to be held at the University of Utah in Salt Lake City, Utah.
Nov. 5:
U.S. voters will head to the polls on election day to choose their next president.
With reports from Adrian Morrow, Paul Koring, The Associated Press and Reuters