PHILADELPHIA — In the place where America’s democracy took root, with tens of thousands shivering in the cold, Barack and Michelle Obama passed the torch to Hillary Clinton in an emotional but anxious plea to elect her president.

Though the book won’t close on his presidency until Inauguration Day, Obama’s frenzied, last-minute push for Clinton was a farewell tour of the nation. As he crisscrossed Michigan, New Hampshire and Pennsylvania Monday, he waxed nostalgic, told old stories and teared up as he thanked the nation for betting, improbably, on “a skinny guy with a funny name.”

He said he’d been asked recently whether the hope that defined his campaign had somehow survived eight trying years.

“The answer’s yes,” Obama said in Independence Mall, not far from the Liberty Bell. He said he was still a believer, “and that’s because of you.”

“In the letters you’ve written me, in the tears you’ve shed for a lost loved one, I’ve seen again and again your goodness and your strength and your heart,” Obama said.

Then the Obamas and the Clintons embraced onstage: The last Democratic president and the current one; the first black president and the woman who, on Tuesday, may break yet another historic barrier.

It was left to Michelle Obama, whose visceral speeches this campaign hit a nerve with many Americans, to cast both families as part of a singular American story: One of inclusive opportunity that she hoped would contrast powerfully with the vision of Republican Donald Trump.

She said she marveled at a country where “a girl like me from the South Side of Chicago, whose great-great-grandfather was a slave, can go to some of the finest universities on earth. Where the biracial son of a single mother from Hawaii and the son of a single mother from Hope, Arkansas, can both make it to the White House.”

“Thank you for welcoming us into your communities, for giving us a chance whether you agreed with our politics or not,” Mrs. Obama said, in her own send-off to the nation. She said ensuring Clinton wins the election was “perhaps the last and most important thing that I can do for my country as first lady.”

It wasn’t always this way. In 2008, when Obama defeated Clinton in a grinding primary, there was naked bitterness between the two Democrats that only began to soften when Obama named her secretary of state.

Nearly a decade later, the Obamas need Clinton as much as she needs them, to prevent their legacy from being eviscerated by a victorious Trump. After all, the president told supporters earlier in Ann Arbor, Michigan, all his accomplishments “go out the window if we don’t win tomorrow.”

Clinton, too, was meditative about the bruising battles that have led her to this moment.

“I regret deeply how angry the tone of the campaign became,” Clinton said, without naming Trump. In a less-than-subtle display of political symbolism, she spoke from behind the presidential seal affixed to the podium from which Obama introduced her.

The Obamas are keenly aware that whether or not Clinton wins Tuesday, their era is coming to an end, a reality punctuated by both Obamas’ insistence that neither will ever run for office again.

So in a parting gift to Clinton, Obama offered her his campaign mantra — “Fired up, ready to go” — and told rally-goers in New Hampshire how it had been coined by a supporter he’d never met who showed up at an obscure event eight years ago in South Carolina.

“It just goes to show you how one voice can change a room,” Obama said — and then a city, a state and a nation. “And if it can change a nation, it can change the world.”