In just a few hours, the people of Iowa will give their verdicts on who they would like to see as candidates in the 2016 Presidential election. After months of campaigning, this is the first real test of public opinion.
Thousands will caucus across the mid-west state for both the Republicans and the Democrats.
Al Jazeera's Alan Fisher has been following the Republican campaign and here he gives his predictions on how things are going to turn out.
There are a number of reasons why the eventual winner in Iowa is tough to call - not least because this is a race unlike any other. I've made predictions on what I've seen, what I've heard and what I've read.
JEB BUSH: Has finally started to gain momentum in the right direction after plunging in almost every poll since late summer. A good debate performance in Des Moines last week will have helped, but he still sees more potential in the next contest in New Hampshire rather than Iowa, which tends to attract more right-wing, evangelical voters. No matter what happens here, the former Florida Governor is staying in for a few more rounds yet. LIKELY FINISH 5th
BEN CARSON: The retired neurosurgeon has been around the top of the polls since the summer, but the debates have exposed his weakness on foreign and economic policy. He needed a win in Iowa to gain momentum for his campaign. It's not going to happen. His run could end here. LIKELY FINISH 4th
CHRIS CHRISTIE: Another who sees better prospects in New Hampshire. He's spent time in Iowa, had reasonable debate performances and was the man many wanted to run four years ago. A finish outside the top half of the contenders will not hurt him as badly here as it would others. LIKELY FINISH 6th
TED CRUZ: Hard one to make a final call on. Started the year topping many of the polls in Iowa but there is a feeling that the Texas senator may have peaked too early. In the absence of Donald Trump at last week’s debate, he was the target of most of the attacks from others. He remains the name I've heard most from activists in the state and has one of the best organisations, geared to getting people out to vote for him. Could still be topped by the Trump bandwagon but I think his ground game might just give him the edge. LIKELY FINISH 1st
CARLY FIORINA: The former businesswoman had her best moment early in the campaign and has failed to recapture the sparkle or the momentum. She has campaigned strongly but just hasn't done enough to suggest she would be a better candidate in any of the areas the voters care about. This is where her White House dream will end. LIKELY FINISH 10th
MIKE HUCKABEE: Surprisingly won the Iowa caucus eight years ago. Remains popular in the state, but really only has a small band of supporters. Said that anything less than a top three finish would mean the end of his campaign. The former Arkansas Governor will be another signing off here. LIKELY FINISH 8th
JOHN KASICH: The Ohio Governor can't quite understand why he is not doing better as he sees himself as the Republican in the field most likely to win the White House. Another who has concentrated more of his efforts in New Hampshire and does well in the polling there. A low finish won't trouble him, which is just as well as that's where he's headed. LIKELY FINISH 9th
RAND PAUL: Had perhaps the best performance in the final debate before Iowa last week. Will tap in to the support built up by his father's presidential run four years ago. The Kentucky senator sees a better chance of success in the caucuses in western states. Is running a low-cost campaign so can keep going for a while but still no chance of the nomination. LIKELY FINISH 7th
MARCO RUBIO: Has been building momentum at the right time. Is still the most likely figure to emerge as the "establishment" candidate to face down the outsiders like Trump and Cruz. But the questions over his stance on immigration still leaves many in his party wary. Can see him picking up a number of 2nd and 3rd place finishes - but at some point he needs a breakthrough and actually win a state, and I’m not quite sure where that happens. LIKELY FINISH 3rd
RICK SANTORUM: Against the odds, he won the Iowa caucuses four years ago. Then the former Pennsylvania senator went from single digits to be the biggest challenger to Mitt Romney. He believes that he can catch lightning in a bottle one more time, but has been passed by others. His moment has gone.
LIKELY FINISH 11th
DONALD TRUMP: This will be the real test for of Trump’s hype and unorthodox campaign strategy. Does he have fans, who turn out to rallies to see the show? Or does he have supporters, who are willing to put in the work and actually get out and vote. Has dominated the headlines for months. But his organisation on the ground is not where it needs to be. He will be hoping for a last-minute surge of people turning up to cast their votes. If that happens, he could actually win the state. But if he loses, he could be seriously damaged. How can you talk about being "America’s most winningest President" but lose your first real test. Could still top Cruz but on the basis of existing evidence. LIKELY FINISH 2nd