A massive plume of white steam is exploding into the cold blue sky above Cedar Rapids this afternoon. It's the byproduct of a corn processing plant, one of the many factories that keep people employed in this small industrial city.
With about 24 hours remaining to the caucuses, hundreds of residents are pouring into the magnificent Veterans Memorial Building, walking past campaign workers bearing huge signs emblazoned with the word HOPE.
Standing on a raised platform inside the hall, flanked by Roman columns 50 feet high, is . Hundreds of people are his feet, cheering him as he calls them to what he calls "a higher purpose."
"We are at a defining moment in our history," he tells them. "Our nation is at war. Our planet is in peril. The dream that so many fought for feels like it's slipping away."
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Earlier in the year, the candidate toned down his oratory in an effort to let the substance of his proposals come through. That's clearly fallen by the wayside in the feverish last moments of this campaign.
"There is a moment in the life of every generation, if we are to make our mark on history, where that spirit of hope has to come through. Where we discard the fear and the doubt and the uncertainty. Where we go ahead and say 'yes we can, we can do this, we believe.
"This is our moment. This is our time."
The crowd explodes. "Lets go change the world," he says.
His evocation of hope and history is intoxicating, even if it raises the expectations of his young followers impossibly high. It certainly explains his almost cult-like following.
"We had a Clinton event in this building a while back," a lighting technician tells me. He describes a polite affair, with a large contingent of senior citizens. "If that crowd was here tonight they'd ask you to turn down the music."
At a event a few hours earlier, the warm-up act consisted of two senior citizens playing accordions. The audience skewed a little older than the Obama crowd, though not as much as the technician's caricature suggested.
If anyone, it was the candidate who played the role of cranky adult, pressing her signature line this season. "Some think you bring about change by hoping for it. I think you bring change by working really, really hard for it."
Squeezed by Obama's call to a generation, this feminist icon spent her last remaining campaign moments here implicitly chiding her younger opponent for his lack of experience. To prove the point, she methodically recited her past accomplishments in punishing detail ("I'll never forget hosting a meeting in Belfast…").
Her audience was large, adoring and eager to applaud generously at times. But the contrast in energy levels between the Clinton and Obama events was vast, the difference between a jazz performance and a rock concert.
I meet a retired piano teacher named Dorris Hochkiss at the Obama rally. She'd spent the day watching both candidates in action. "He was more inspirational," she says. She searches for a word for Clinton. "She was very…informative."
It's far from clear what all this adds up to, exactly. Watching Obama, you can be forgiven for thinking of Gene McCarthy and Howard Dean, exciting a generation of young people on their marches toward political oblivion.
"The opposition would have you believe it doesn't mean a thing," says David Axelrod, Obama's strategist, chatting above the roar of Obama's audience. "We'll see soon enough."
Watching the candidate in action, you can also find yourself pondering all sorts of unanswerable questions about the difference between campaigning and governing. What if the guy just knows how to give a good speech? Is he decisive? Seasoned? Ready?
The Clintons have been pouncing on this vulnerability with a vengeance. "In theory," Bill Clinton suggested to Charlie Rose, "we could find someone who is a gifted television commentator."
At one point in Obama's performance I glance at an email from the Giuliani campaign hailing a new campaign commercial.
"A nuclear power in chaos. Madmen bent on creating it. Leaders assassinated. Democracy attacked. And Osama bin Laden still making threats. In a world where the next crisis is a moment away… America needs a leader who's ready."
The video is a rabid collage of explosions and assassinations, ending with the image of the Trade Towers after the attack. Its excesses aside, it makes you wonder how Obama would survive a Republican onslaught on his credentials.
I raise the issue with one of Obama's fans, an attorney named Lee Courier. "I'm not caught up in the experience trap," she says. "Kennedy didn't have experience. And look at some of those who did, and who failed.
"I think this is a time for inspiration," she says. "And this is a guy who's really inspiring me."
Tonight, we may learn how far inspiration can take you.