Battle commences for the soul of the Democratic Party
Video report by ITV News Washington Correspondent Robert Moore
Here in Iowa it’s unseasonably warm. No Arctic wind whistling through the prairies, and no deep snow for the presidential contenders and voters to contend with.
But there is a distinct chill within the Democratic Party with hours to go before the first votes are cast in the caucus here.
The competition is too fierce, and the stakes are too high, for friendships to survive.
The party faces deepening rancour as it tries to find the best candidate to beat Donald Trump in November’s election.
The early non-aggression pact between two most radical contenders for the nomination - Senator Elizabeth Warren and Senator Bernie Sanders - has been abandoned.
They are fighting for the same bloc of voters, those who see America as a corrupt oligarchy defined by inequality and injustice.
US presidential election explained: What is the Iowa caucus?
Who are the Democratic candidates seeking the party’s presidential nomination?
Sanders has also fallen out - spectacularly so - with Hillary Clinton, the 2016 nominee.
She recently declared that no one likes Bernie and that the Vermont Senator has achieved nothing with his crusading brand of politics.
His ferociously loyal supporters - young, radical and utterly devoted - are furious with Mrs Clinton.
They see her as the ultimate establishment figure who has profited from her celebrity and who only has herself to blame for the catastrophic defeat of 2016.
Then there are the main centrist contenders for the nomination: Joe Biden, the former vice president, and Pete Buttigieg, the startlingly young former mayor from Indiana.
They are circling each other warily, both needing the campaign of the other to collapse.
It is increasingly clear that the Democrats are going to be engaged in a long internal ideological fight before they can focus on ejecting Donald Trump from the White House. That struggle for supremacy could last all the way to the Democratic Party convention in the summer.
Iowa will give us no knock-out punch tonight. This is a marathon, not a sprint. But it will offer some valuable first clues.
Do Democrats want to veer to the left and adopt a radical agenda that will fire up the young and the angry, but scare the living daylights out of independent voters?
Or do they want to play it safe with a mainstream candidate who will appeal to centrist voters, but who will fail to fire up the despondent base of the party?
The wounds of 2016 - the trauma of losing to Donald Trump - have not healed. In fact, the campaign to make him a one-term President is opening up the old scar tissue.
Iowa is meant to be clarifying in a Mid-Western sort of way, where fresh faces and bold ideas are road-tested by sensible, regular folk from the heartland.
This time, there may be no clarity or wisdom emerging from the prairies. Iowa may only add to the immense confusion and anxiety that Democrats have been feeling for three long years.
The biggest fear of Democrats is simply stated: Dear God, what happens if we nominate someone again who can’t defeat Donald Trump? What then?