It was 37 degrees, and he warmed his left hand in his pocket even as he jabbed at the air with his right. Midnight was approaching. It was the last rally of the last Saturday of his last campaign, and he drifted off script.
"I was backstage with David Plouffe," Mr. Obama told the crowd, referring to his political guru, who looked surprised as he stood offstage. "And we were talking about how, as the campaign goes on, we've become less relevant. I'm sort of a prop in the campaign. He's just bothering a bunch of folks, calling, asking what's going on."
Indeed, for Mr. Obama, the campaign is effectively over. Oh, there will be a final round of rallies on Monday, a final frenetic swing through swing states and plenty of Plouffe phone calls asking what is going on. But the machinery they have assiduously put in place over four years is now on remote control. The campaign is out of their hands, and so is the fate of the 44th president.
Win, and he has a chance to secure a legacy as a president who made a mark not simply by virtue of his original barrier-breaking election but also by transforming America in his image - for the better, he hopes; for the worse, his critics fear. Lose, and he becomes an avatar of hope and change who could not fulfill his own promise and whose programs might not survive his remarkable rise and fall.
It is in moments like these that nostalgia takes hold for a president on the precipice. With each passing day, aides said, Mr. Obama has taken note every time he passes a milestone.
"This is my last debate prep practice," he said at Camp David.
"This is my last walk-through," he said, touring a debate stage.
"This is my last debate," he said after squaring off a third time with Mitt Romney.
The "lasts" piled up on a bone-weary final weekend as he raced from Ohio to Wisconsin, Iowa to Virginia, New Hampshire to Florida and back to Ohio, then Colorado and Wisconsin again. What he hopes most is that these are not the last days of his presidency.
"You can see the nostalgia, the wistfulness, setting in," observed Dan Pfeiffer, one of his longest-serving advisers and now the White House communications director. "The focus here is winning and making the case, but the last campaign of a man's life - you every once in a while pause and think about that."
Other than a brief interlude for Hurricane Sandy, the White House has been relocated to Air Force One for months. Mr. Obama half-jogs off the plane and half-jogs onto the stage, his coat off, his sleeves rolled up, his tie usually gone. He has grown hoarse arguing his case. Between stops, he huddles in the plane's conference room, nursing his throat with tea and scratching out his speech in longhand.
His daily routine has been upended, but he tries to keep up his workout regimen in hotel fitness centers. He eats whenever he can, usually whatever the Air Force stewards are serving aboard the plane or something brought in before a speech. Occasionally, when he stops to glad-hand at a pizza place or a doughnut shop, he may snack in the motorcade to the next campaign rally; at a Cleveland meat shop, he bought barbecue jerky.
He is happier whenever he gets time with Michelle Obama, but she has largely kept a separate schedule. Like any father on the road, he makes sure to call his wife and children every evening. To keep him company in recent weeks, friends like Marty Nesbitt and Mike Ramos have accompanied him aboard Air Force One. Between conference calls on storm recovery on Sunday, he checked out the Chicago Bears football game on the Air Force One television.
The other day, Mr. Obama landed in Chicago to vote and spotted his former chief of staff Rahm Emanuel, now the city's mayor, waiting on the tarmac. A huge grin appeared on the president's face, and he pointed at Mr. Emanuel. The mayor grinned and pointed back. The two embraced like long-lost brothers and chatted happily before walking, arm in arm, to shake hands with bystanders.
"He's got his goal in eyesight, and he's driving to the basket," Mr. Emanuel said later. "He's a happy warrior, I'd say."
Happier with the debates over. He considered preparations for the first one "a drag," as he put it, and got walloped. It was an eye-opener for a president who has never lacked confidence, a moment when he "faced his own political mortality," Mr. Pfeiffer said. "The first debate turned a switch for him. He came out of that very focused on ensuring that would never happen again." By his own reckoning, Mr. Obama had failed to "communicate why he wants a second term," said another adviser.
Senator John Kerry of Massachusetts, who played Mr. Romney during debate rehearsals, said Mr. Obama recognized the peril. "He just decided in his mind that he needed to bear down and win, period," Mr. Kerry said in an interview. "He's a competitive guy. He's very analytical. He knows exactly what he had not done and exactly what he wanted to do."
After coming out stronger in the later debates, Mr. Obama could finally return to the trail, where the affirmation of the crowd beats the pounding of the pundits. The crowds are smaller - he drew 24,000 here in Bristow, compared with 60,000 and 80,000 in his final days in 2008 - but they are enthusiastic, and he draws energy from them.
"The president seemed relaxed," said former Gov. Ted Strickland of Ohio, who campaigned with him in that state. "You don't see a lot of anxiety or frenetic behaviour."
Mr. Obama seems to enjoy his unannounced stops even more, allowing a tiny peek into his interior life. At the Common Man restaurant in Merrimack, N.H., he met a woman with two daughters. "You can't beat daughters," he said, reflecting on his own, who were, he added, still at a good age: "They still love you. They're still cute. They don't talk back too much."
One of his favourite stops was the employee cafeteria at the Bellagio hotel and casino in Las Vegas, where he greeted kitchen workers and room cleaners. "For him, that was the people he's fighting for," Mr. Plouffe said later. "He loves stuff like that. That was a unique one."
It made such an impression that Mr. Obama was still talking about it a day later. "That thing at the Bellagio yesterday was great," he told reporters on Air Force One. Then, recalling that his press secretary's van broke down, he joked, "I think every trip we're going to find at least one occasion to ditch Jay Carney."
Very rarely does Mr. Obama confront the nearly half of America that polls say do not support him, those who blame him for the economic troubles still afflicting the country. He seemed taken aback at Cleveland's West Side Market when he asked a chicken vendor how business was going.
"Terrible since you got here," the man said.
The vendor later told his local newspaper he had meant only that the president's party had blocked his business that day. But he inadvertently voiced the frustrations of many Americans.
Nor has Mr. Obama faced many tough questions lately, like those about the response to the attack in Benghazi, Libya, since he generally does not take questions from the reporters who trail him everywhere.
Instead, he sticks to generally friendlier broadcast interviews, sometimes giving seven minutes to a local television station or calling in to drive-time radio disc jockeys with nicknames like Roadkill.
With Michael Yo, a Miami radio host, he revealed his first job - Baskin-Robbins, "paid minimum wage" - and addressed a feud between Mariah Carey and Nicki Minaj: "I'm all about bringing people together," he said.
He relishes rare moments away from politics. He had dinner one night at a Washington restaurant with several swing-state Democrats who had won a contest to meet the president. He had done his homework; he knew their names and their children's names. But as he tucked into a dinner of salmon, asparagus and potatoes - he left most of the potatoes - he was eager not to dwell on the campaign.
"We didn't really talk about politics very much," said Kimberley Cathey, 41, a speech language pathologist from North Carolina. "I don't recall really in the hour and a half we talked anything major about the election," said her husband, Ron, also 41. "It was pretty much a night away from that."
The president did contemplate the possibility of defeat, but said he and his family "would be fine no matter what the outcome," Ms. Cathey said. Mario Orosa, 44, a technical specialist at the Goodyear Tire and Rubber Company in Akron, Ohio, said he had asked Mr. Obama, "What was the last thing that made you really nervous?" The president replied, "I don't remember."
He is not a nervous man. But even his famous cool may be challenged on Tuesday night. For the "prop," it is all over but the waiting, while Mr. Plouffe makes some calls and bothers some more folks.