After more than a year of campaigns and constant debate, the Republicans vying for the White House will finally be tested at the ballot box and see if they have a chance against Donald Trump.
On Monday, thousands of Iowa voters will head to 1,657 precincts across the freezing, snowy state to decide who they will vote for as the Republican candidate for president.
At 7 p.m. Central Time (8 p.m. Eastern Time), they gather in churches, high schools, gyms and golf courses to write their preferred candidate's name on a blank piece of paper in a tradition that dates back to 1972.
Iowa's position at the start of the primary calendar gives it and its three million residents an outsized but critically important role in selecting the Republican candidate.
The winner will gain crucial momentum and up to 40 delegates to the convention as the candidates head to votes in larger states.
The 77-year-old former President Trump has a significant lead in polls over the rest of the field, with Nikki Haley and Ron DeSantis vying for second place.
But the caucus's history of chaos, upsets and voting disruptions means several surprising outcomes are still possible.
Did Ron DeSantis' persistent campaigning do enough to get him into the race? Will Nikki Haley continue to build on her momentum following Chris Christie's exit?
Can Trump live up to sky-high expectations and secure his biggest victory since Bob Dole's 12-point victory over Pat Buchanan in 1996?
breaks down what to expect on Monday night and when we can see the results:
On Monday, thousands of Iowa voters will head to 1,657 precincts across the freezing, snowy state to decide who they will vote for as the Republican candidate for president
When do the primaries begin and when will the winner be announced?
As with many recent US elections, there will be a dramatic wait for the result, which could last less than an hour or possibly days.
The Iowa Republican caucus begins at 7 p.m. local time (8 p.m. ET). Participants must be in their chosen local district by then to hear the speeches before casting their vote.
Volunteers or caucus captains enter the count into an online system and the final results are posted on an Iowa Republican Party website.
Results from the smaller counties will be available in about 30 minutes, while the larger counts may take hours.
We may know the winner on Monday night, especially if Trump is ahead by an insurmountable margin.
It could be a very long night if there are problems or it's a close contest, and Iowa has a history of late (or wrong) results.
Ron DeSantis, his wife Casey and their son Mason brave the snow to campaign in snowy Urbandale, Iowa
Iowa struggles in 2020, 2016 and 2012 that could lead to a long night
In 2020, Pete Buttigieg won the Democratic caucus, but issues dominated the vote.
There were widespread problems with the vote counting app and inconsistencies in the data received from counties.
Buttigieg declared victory over Bernie Sanders that night, but who won the exciting contest was always in question.
In 2016, the Iowa Democratic Party declared Hillary Clinton the winner over Sanders at 2:30 a.m.
The Associated Press, the news agency that normally announces the winner, did not confirm the result until the next day.
In 2012, the GOP called it the wrong result.
The party declared Mitt Romney the winner that night by eight votes, but two weeks later a recount revealed that Rick Santorum had emerged victorious.
A botched result could have a significant impact on the race, as the declared winner will have momentum in the Iowa caucuses a week later.
What is a caucus and how is it different from a primary? A tradition that goes back to Jimmy Carter
The word “caucus” is believed to come from a Native American term, an Algonquin reference to a gathering of tribal leaders.
Instead of polling places, the Midwestern state has polling places, including school gyms, public libraries or a family kitchen.
People go to their local caucus site at a certain time in the evening and a representative from each candidate speaks to them.
They then cast their votes and the results at each location or district are counted.
In the past, due to the small number of voters, tied votes were decided by a coin toss.
The system is different from a primary election, where polls are open all day and voters can cast mail-in ballots.
The local party runs it while the state runs the primaries. The vast majority of states have primary elections.
Will the brutal winter weather have an impact? Forecasters expect Monday to be the coldest election campaign in history
Monday's caucus will likely be the coldest in history. Temperatures will drop below freezing and wind chill will make it even colder.
Candidates had to cancel events because of the snow, devastating their final bids for Iowans.
Voters must be at the precinct in person, so they will have to navigate the snow to arrive on time.
Iowa voters are used to the conditions and take the responsibility of voting seriously.
Experts assume that this will have little impact on voter turnout. There are 757,200 registered Republicans in the state and record turnout was 187,000 in 2016, when Ted Cruz defeated Trump.
Earlier this week, top Republican strategist Jimmy Centers (who doesn't align with either candidate) told that a robust ground operation was critical and that Trump was the best candidate.
“DeSantis has built a really strong organization, with caucus site captains for each site across the state,” said Centers, former communications director for Iowa Gov. Kim Reynolds.
“In any other year, this would be the gold standard for a caucus organization.” “Former President Trump's team has the advantage of having worked for the state for eight years and built deep, meaningful relationships across the state.”
Giovanni Gonzalez shovels his sidewalk during snow on Friday in Sioux City, Iowa
Can anyone beat Trump in Iowa? He is ahead in the polls by an average of 30 points
The polls point to no, but Iowa has delivered many shocking results.
An average of recent polls shows Trump at 51 percent, ahead of Ron DeSantis at 19 percent and Nikki Haley at 16 percent.
It's been like this for many weeks.
Iowa observers note that the electorate can only get behind a candidate very late.
The amount of time a candidate spent in the state meeting voters in person also shouldn't be underestimated, and Trump visited less than his rivals.
DeSantis completed the “full Grassley” tour, named after state Sen. Chuck Grassley, which means visiting all 99 counties in the state.
A lot also depends on how well a campaign gets its voters to campaign pages.
Many people have other obligations or a lack of child care on a cold January evening.
However, Gentry Collins, a veteran Republican strategist who ran Mitt Romney's 2008 caucus campaign, said: “It looked to me for a long time like there was a narrow path, but there was a path for a non-Trump candidate.”
“But there’s not really a single alternative that people can advocate for.”
An average of recent polls shows Trump at 51 percent, ahead of Ron DeSantis at 19 percent and Nikki Haley at 16 percent. It's been like this for many weeks
What does the Iowa winner get? How does it help in the nomination process?
At stake are 40 delegates that Iowa sends to the Republican National Convention, who in turn will help nominate the party's presidential candidate.
The 40 delegates are allocated pro rata, so the winner doesn't have much of an advantage.
In 2016, Ted Cruz won Iowa with 27.6 percent and received eight delegates.
Donald Trump and Marco Rubio, who came second and third, got seven each.
After the chaotic 1968 Democratic National Convention, the party decided to expand the nomination process.
Iowa had a complex process and was therefore allowed to be approved first in 1972.
The Republican Party also put Iowa first in 1976, and it has remained that way ever since, despite complaints from other states.
Critics say the Midwestern state is not representative of the rest of America and doesn't have enough people to justify its position early in the electoral calendar.
Why is Iowa so important? The so-called “Big Mo” for the winner
Iowa's 40 delegates represent just 1.6 percent of the total number of delegates sent by all states to the Republican National Convention to choose the presidential candidate.
However, Iowa is seen as a testing ground by candidates, donors and political strategists because it provides the first real outcome of the process.
The winner gets momentum – what George HW Bush called “Big Mo” after his victory in Iowa in 1980.
Donors who have been on the fence are starting to give money to the winner, while candidates who aren't doing well in Iowa are being pressured to drop out.
Nikki Haley had to cancel in-person events on Friday due to the snow, but she is hoping for the latest upswing
Does Iowa predict the winner? The very mixed results of the caucus
Iowa's reputation for predicting the final White House seat rests on the surprising rise of the little-known Georgia governor, Jimmy Carter, who unexpectedly won the 1976 election.
The winner of Iowa was elected president only three times.
The state's balance sheet has not been very successful, especially recently.
Donald Trump lost Iowa to Ted Cruz in 2016 but still won the White House.
Neither Huckabee nor Santorum secured the Republican nomination.