The supremely confident demeanour and exalted rhetoric of the Democratic nominee at a New Hampshire event betrayed that he is a man convinced he is poised to make history. While his Republican opponent John McCain, trailing in the polls, is pursuing a strategy of eking out a victory in traditional swing states, Mr Obama is transferring resources to conservative strongholds like Georgia, West Virginia and even Kentucky in pursuit of a landslide victory.
Speaking in an apple orchard against the picture-perfect New England backdrop of an red, green and yellow autumn foliage on a stage adorned with pumpkins and hay bales, Mr Obama reminded voters of the dangers of hubris.
Polls indicated that the young Illinois senator was cruising towards a crushing victory over Hillary Clinton in the state's Democratic primary. His rallies were two or three times the size of hers. The media had declared him the victor, a conclusion shared by Obama aides.
On election day, however, Mrs Clinton won. "We are 19 days away from changing this country. Nineteen days away. But for those who are getting a little cocky, I've got two words for you: New Hampshire," said Mr Obama.
"I learned right here, with the help of my great friend and supporter Hillary Clinton, that you cannot let up, you can't pay too much attention to polls. We've got to keep making our case for change. We've got to keep fighting for every single vote. We've got to keep running through the finish line."
At a glitzy fundraising event in Manhattan at which Bruce Springsteen and Billy Joel performed Mr Obama warned high-roller supporters: "Don't underestimate the capacity of Democrats to snatch defeat from the jaws of victory. Don't underestimate our ability to screw it up."
But much of Mr Obama's speech in Londonderry - punctuated by cries of "We all love you Obama", "I love you" and "We will work with you" - was devoted to the kind of quasi-religious sentiments and motivational-coach style exhortations, the kind of pride that set him up for a big fall in January.
"I want you to believe," said the candidate, clad in an open-necked shirt and barn jacket. "Not so much believe just in me but believe in yourselves. Believe in the future. Believe in the future we can build together. I'm confident together we can't fail."
There was a carnival atmosphere among the crowd of some 4,000, who almost drowned Mr Obama out as he reached his crescendo and said: "I promise you. We won't just win New Hampshire. We will win this election and, you and I together, we're going to change the country and change the world."
Mr Obama was described as "preternaturally confident" in a gushing endorsement by the Washington Post on Friday.
His supreme self-belief has also been the target of late-night comedians. "With just 19 days left until the election, Barack Obama warned supporters today to guard against overconfidence," Amy Poehler of Saturday Night Live reported.
"Then he boarded Air Force One, blasted 'We Are The Champions' and shouted 'I'm King of the World'."
Both Democrats and Republicans in New Hampshire appear convinced that Mr Obama will win.
"We feel we're on the brink of a whole new life in this country," said Betsy Whitman, 69.
"Sure, he'll win," said Marlene Hulme, 70, at the Londonderry event. "Our expectations were high today and he knocked it out of the park."
A lone McCain supporter at the rally said she too was convinced that the Republican nominee was finished. "McCain has lost," said Deborah Barnhart, 48, who runs a landscaping business.
"He's lost because the Messiah has spoken and we're going to change the world. That's all people want to hear after eight years of Bush. Obama thinks he's won. Everyone here thinks he's won."