ANN ARBOR, Mich. — President Obama was feeling a little sentimental.
His shirt sleeves rolled up, his vowels slipping off the ends of his words, his last day on the campaign trail finally here, Mr. Obama soaked up an unseasonably warm autumn sun on a baseball field at the University of Michigan on Monday, and drank in the energy of his political finale.
“We’ve got one more day, Michigan — one more day,” he said, gazing out over a crowd of more than 9,000at midday. But Mr. Obama was not quite ready for it to be over.
“This is gonna be my last” — he caught himself — “probably my last day of campaigning for a while.”
For Donald J. Trump and Hillary Clinton, Monday’s cross-country travels were all about tomorrow. For Mr. Obama, his travels here to Michigan, and then to New Hampshire and Philadelphia, were part victory lap and part nostalgia tour, as he was accompanied on Air Force One by some of his longest-serving aides, and was ushered in and out of rallies by the same U2 and Bruce Springsteen anthems that were the soundtracks of his campaigns.
But his core mission was to implore voters across the country to rally behind Mrs. Clinton on Tuesday, or see the values and ideals that fueled his rise and powered his agenda defeated. So Mr. Obama stumped on Monday with the fervor of a man battling to preserve his legacy and with the joy of one who has watched his approval ratings tick higher as the presidential race’s tenor has sunk ever lower, savoring the almost palpable sense at Mrs. Clinton’s rallies that Americans will miss him when he is gone.
“Whatever credibility I’ve earned after eight years as president,” Mr. Obama said, “I am asking you to trust me on this one.”
“I already voted,” he added. “I voted for Hillary Clinton, because I am absolutely confident that when she is president, this country will be in good hands — and I’m asking you to do the same.”
“I love you!” supporters kept shouting at the president as he turned serious to lay out the stakes of an extraordinary race.
“I love you back — I do,” Mr. Obama said in Michigan. “But tomorrow, you will choose whether we continue this journey of progress, or whether it all goes out the window.”
Nostalgia aside, there was no mistaking the seriousness of his message. Mr. Trump could never be trusted with control over the nation’s nuclear arsenal, the president said, if his own staff regarded him as too temperamental to use restraint on social media.
“Over the weekend, his campaign took away his Twitter account,” Mr. Obama said, referring to a report in The New York Times about the closing days of Mr. Trump’s campaign. “Now, if your closest advisers don’t trust you to tweet, then how can we trust him with the nuclear codes?”
“Donald Trump is temperamentally unfit to be commander in chief,” Mr. Obama said. “He’s unqualified to be America’s chief executive.”
Mr. Obama began his day at the White House, striding out of the residence to board Marine One just after 9:30 a.m. to begin his final campaign sprint. He rarely paused in the hours that followed, jetting from state to state on Air Force One, speeding from airport to rally site and back again in his armored limousine, racing against the clock on a historic presidential contest and his own campaign denouement.
In New Hampshire, his motorcade rushed at sunset down roads flanked by flaming-red and burnt-orange foliage to deliver him to a rally that drew more than 7,600. At the airport in Portsmouth, he confessed to a young boy who asked about the presidential jumbo jet that he was reluctant to relinquish Air Force One.
“I am going to miss this plane,” he told the boy with a smile. “I only have it for a few more months.”
His itinerary on Monday took the president to three states that he won in 2008 and 2012, and that are now crucial bulwarks for Mrs. Clinton. All three are also places where it is more difficult for Democrats to turn out their core supporters because they do not offer early voting.
“It’s not that often you get the chance to move history in a better direction,” Mr. Obama said. “This is one of those moments. Don’t let it slip away.”
In Michigan, he allowed himself a few moments to gloat, reminding voters of all that his administration had done to pull American automobile makers from the brink of bankruptcy.
“I think I’ve earned some credibility here,” Mr. Obama said tartly, repeating the phrase three times as he checked off the metrics of a resurgent automobile industry and recovering manufacturing sector.
He returned to his trademark campaign-trail catchphrases. As he elicited jeers by reciting a litany of criticisms of Mr. Trump — his not paying taxes, his comments about immigrants, women and Muslims — Mr. Obama barked, “Don’t boo. Vote!” He sparked chants of “Yes we can!” and “O-BAM-A.”
In Durham, N.H., he returned to the now-familiar story about how his 2008 campaign found its signature “Fired up! Ready to go!” theme, borrowed from a woman in a small town in South Carolina, whom he met after getting soaked in a driving rain to attend a gathering of only about 20 people.
“Every meeting she goes to, she does this thing” of chanting the refrain, Mr. Obama said. “Which is kind of strange. But the thing is that after a while, I get kind of fired up,” Mr. Obama said. “I’m starting to feel like I’m ready to go.”
When he retired to his cabin on Air Force One, Mr. Obama sat with senior adviser Valerie B. Jarrett, a confidante whose friendship with Mr. Obama dates to his Chicago days, and Susan E. Rice, his national security adviser. Brian Deese, his senior adviser for climate change, came too, along with Josh Earnest, the White House press secretary who has been with him throughout his presidency, and David Simas, his political director.
But it was in the thronging crowd that Mr. Obama seemed to relive his campaign experience most poignantly.
In Ann Arbor, he lingered for several minutes after he finished speaking, clasping hands with supporters and grinning at them broadly, as the strains of Mr. Springsteen’s “Land of Hope and Dreams” pulsed the stadium, a throwback to four years ago.
Then he turned on his heel to go, and a sudden cheer went up as people throughout the emptying stadium raised their arms and gave the president one final wave goodbye.Julie Hirschfeld Davis reported from Ann Arbor, Mich., and Gardiner Ha