Des Moines, Iowa
At 10:15 P.M. last Tuesday night, Barack Obama was gazing vacantly out the window of a gold Chevy Tahoe as it moved deliberately through the sleet to the Sheraton Hotel in Iowa City. When the large SUV came to a stop in front of the hotel, Obama, wearing just slacks and a white oxford despite the sub-freezing temperature, slowly opened his door and looked at the sliding glass doors some 20 feet away. The expression on his face suggested he was pondering a very serious question: How am I going to find the energy to make it to my room?

But he did it. And as he made his way through the lobby, willing one foot in front of the other, he even summoned enough strength for a wave to the three people working at the front desk. "How's it going, guys?" he said, not worried that one of those he was addressing was a woman. Obama's Secret Service detail held the elevator for him and moments later he was gone.

It was quite a contrast. Just 30 minutes earlier, Obama was standing below a two-story American flag hanging from the jogging track at the University of Iowa Field House. Thousands of young people surrounded him as he explained why he should be president of the United States. They interrupted him more than a dozen times with enthusiastic applause. He had energy to spare and delivered a lively and animated performance.

"I don't want to talk about fear," he bellowed into a handheld microphone, gesturing with an authority that matched his outrage. "I want to talk about the future. Fear of terrorism, fear of immigration, fear of gay people--we don't need a politics of fear, we need a politics of hope."

He had said these same things three hours earlier at a rally on the campus of Grinnell College. Before Grinnell, he had participated in a two-hour debate on National Public Radio. And before that, he gave an interview to the staff of the Des Moines Register. Before it all, he had talked to his strategists about how he would spend the four weeks that remain before the Iowa caucuses on January 3, 2008. He's been doing this--or some version of it--for more than 10 months. But as he stood under the bright lights at the University of Iowa, he gave no hint that he was as exhausted as he would appear when he finally made it to his hotel.

If Barack Obama is to have any chance at winning the Democratic nomination for president, he must beat Hillary Clinton in Iowa. That is not an insight. Everyone from Obama's wife ("Iowa will make the difference. If Barack doesn't win Iowa, it is just a dream") to Karl Rove ("Iowa is your chance to best her. If you do not do it there, odds are you never will anywhere") has noted this.

And no one understands this better than Clinton herself. Two weeks ago, she hired 100 new staffers in the state. Then last week she unleashed a torrent of harsh attacks on Obama and oddly announced to voters that she would enjoy getting nasty. "I have been for months on the receiving end of rather consistent attacks," she said. "Well now the fun part starts."