He had already voted early back home in Chicago, so all that was left for President Barack Obama on Election Day was to take part in the ritual he had observed with his own name on the ballot - a pickup basketball game - and to make a final pitch to the electorate.

"Go vote. It's up to you," Obama said Tuesday, pointing at television news cameras during a stroll along the White House colonnade after returning from the game at Fort McNair.

A reporter asked the president, who has campaigned intensively for Democratic nominee Hillary Clinton, whether he was nervous about the outcome.

"As long as the American people vote, I think we'll do a good job," he replied. "I hope everybody's voted early. If not, get out there."

Obama then disappeared into the White House, but his last minute get-out-the-vote effort had not yet finished. Aides said he taped interviews with six radio stations in three swing states - Pennsylvania, Florida and Ohio - imploring people to get to the polls.

Called upon as a chief surrogate for a candidate who has struggled to make a personal connection with voters, Obama has put his suddenly robust approval ratings and star power to work for Clinton with increasing urgency in a bid to boost Democratic turnout in the race against Republican nominee Donald Trump.

He has pounded the lectern and wagged his finger, given stern instructions and laughed easily, introduced new lines and brought back old ones. When the crowds have called, "We love you!" he still has said, "Love you back" - but has made quite clear he has an ask.

"Tomorrow, you will choose whether we continue this journey of progress," he told the crowd at a Michigan rally Monday, "or whether it all goes out the window."

Sixteen times over the past two months, Obama has delivered his stump speech for Clinton - including three times on Monday in a final swing through Michigan, New Hampshire and Pennsylvania. He and his wife, first lady Michelle Obama, have fanned out across the radio and television airways for dozens of interviews, many with stations targeting African-American audiences. The president attended 72 fundraising events on behalf of Clinton and the Democratic Party, according to party operatives.

In addition, Obama has been briefed daily on the status of key Senate and House races, according to aides, and he gets updates on the battles for control of state legislatures a couple of times a week. He has endorsed a huge slate of Democratic candidates up and down the ballots in states across the country.

"I will consider it a personal insult, an insult to my legacy, if this community lets down its guard and fails to activate itself in this election," Obama told the Congressional Black Caucus in a fiery speech in September. "You want to give me a good send-off? Go vote."

For Obama, who said during his State of the Union address in January that his chief regret is that political polarization has become worse, the campaign appearances offered him a final chance to convince the public that his brand of political optimism would outlast the bitterness and ugly tone of the 2016 campaign season.

But the president acknowledged the skepticism that it would not. At a rally with 33,000 Clinton supporters in Philadelphia's Independence Mall on Monday night, Obama told the crowd that a journalist had asked him last week whether he still believed in the politics of "hope" that on which he campaigned in 2008.

"Maybe your vision was misguided - or at least very naive," the reporter had suggested, according to Obama. The president considered the question out loud for a moment, ruminating over a social-media discourse that sows partisanship and an unbalanced economic system that has left many Americans more skeptical about their futures.

"Despite all that, I told him the answer is, 'Yes, I still believe in hope,' " Obama declared. "I'm still as optimistic as ever."

It has not been an easy sell.

Obama's personal approval ratings, comfortably above 50 percent, are at some of the highest levels since his first year in office. But Clinton and Trump are saddled with far worse approval ratings and even lower levels of public trust.

Which is why Obama's last campaign has been, at heart, less about Clinton and more about his personal connection with the supporters who propelled his unlikely rise.

"I have seen again and again your goodness and your strength and your heart," Obama told the crowd in Philadelphia. "In 2008, you gave me a chance - a skinny guy with a funny name. ... America, I'm betting on you one more time."

Obama used his final barnstorming trip as a chance to thank his supporters and remind them of the high stakes, and he did so with notes of defiance about the prospect of a Trump presidency, and a touch of nostalgia about his own waning tenure in the White House.

"I'm feeling a little sentimental," Obama told a crowd of 9,000 on his first stop, at the University of Michigan in Ann Arbor.

He wasn't the only one. More than eight years after they crowded into staff vans to canvas for votes in rural Iowa, several long-serving White House senior aides joined the president aboard Air Force One for one more get-out-the-vote effort.

"The election of the next president is the clearest, most tangible sign that this presidency is about to end," said White House press secretary Josh Earnest, who knocked on doors for Obama in Iowa in 2007. "It's a moment for reflection."

The nostalgia was flowing heavily in both directions. On Obama's second stop Monday, at the University of New Hampshire, a supporter in the crowd of 7,600 held up a blue sign from the president's 2012 reelection campaign. "Four more years!" someone else shouted.

Others, especially in the African-American community, have urged Michelle Obama to consider a run for political office. She has demurred. But the mother of two teenage daughters has become perhaps the Democratic Party's most potent messenger in making a personal case against Trump as a dangerous role model. Her use of the Obama family motto - "when they go low, we go high" - during the Democratic National Convention in July became a rallying cry.

The president told his college audiences that the election amounted to a referendum on the progress of the past eight years. "C'mon, man," he declared sarcastically on several occasions in exasperation at the notion that Trump could be taken seriously, given his lewd comments about women and insults against racial minorities.

Offering a refresher course for students who were perhaps too young to remember much about the state of the nation when he took office, Obama recited a litany of accomplishments: rescuing the economy from the Great Recession, bailing out the auto industry, passing a landmark health care law, killing al-Qaeda leader Osama bin Laden.

When the crowd booed a mention of Trump, the president recycled a 2012 campaign refrain: "Don't boo - vote!"

Trump "can't hear you boo, but he can hear you vote," the president said, jabbing a finger in the air.

Throughout the campaign, the president has warned against complacency. Winding up his remarks in New Hampshire, Obama retold the story of how he was inspired during a low moment in his 2008 campaign by the chant of a diminutive county council member in Greenwood, South Carolina, named Edith Childs who was known to energize a room by shouting, "Fired up! Ready to go!"

Emphasizing the power of a single voice to make a difference, Obama implored his audience to go to the polls: "Let's go finish what we started."

But, before it was time to vote, there was one final stop in Philadelphia, where a sea of supporters was waiting for a final glimpse of the first couple.

The Obamas did not disappoint. The first lady took a moment to tell the crowd "how proud I am of all that he has done for this country," and the president responded by calling her "my partner, my love, my rock."

Before long, however, they ceded the stage to Clinton. And when the rally was over, and the Democratic nominee headed off to another rally in North Carolina, the Obamas did not go with her.

The presidential motorcade returned to the airport and the first couple ascended the stairs of Air Force One, which lifted into the night sky, leaving the crowds behind.