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.