Music icon Bruce Springsteen has joined former US president Barack Obama in a star-studded rally for Kamala Harris in the battleground state of Georgia.

At the same rally in the town of Clarkston on Thursday (local time), film director Spike Lee warned a packed crowd of 20,000 not to be “bamboozled” into voting for Republican presidential nominee Donald Trump.

Springsteen, a long-time Democratic backer, performed melancholy laments The Promised Land and Land of Hope and Dreams.

“Donald Trump is running to be an American tyrant. He does not understand this country, its history or what it means to be American,” Springsteen said, as he encouraged the crowd to vote for Harris.

Obama, who has been campaigning in political swing states for Vice President Harris, said Trump thought about no one but himself. He implied that Trump was acting like a doddering old man and noted that Harris had actually worked at McDonald’s during college – while Trump pulled a stunt at the fast food chain earlier this week.

“She worked at McDonald’s when she was in college to pay her expenses. She didn’t pretend to work at McDonald’s when it was closed,” Obama said.

Harris campaign said the Clarkston event was her largest political rally yet, topping the 17,000 that she drew in Greensboro, North Carolina, in early September.

During her speech, Harris attacked Trump by comparing him to the “predators, fraudsters and repeat offenders” she prosecuted early in her career.

“I took them on and I won,” Harris said.

“Well, Georgia, in 12 days, it’s Donald Trump’s turn. It’s his turn,”

“It’s either Donald Trump in there stewing over his enemies list, or me working for you, checking off my to-do list,”

“You have the power to make that decision.”

“Someone who says we should terminate the Constitution of the United States of America should never again stand behind the seal of the president of the United States of America,” Harris said.

“Never again. The consequences of him being president again are brutally serious.”

Celebrity endorsers add cultural cachet to candidates, and have typically helped campaigns raise money, turn out crowds at rallies and generate excitement on social media. For both the Harris and Trump campaigns, they are part of the down-to-the-wire blitz to mobilise voters ahead of election day on November 5.

Thursday’s rally also marks the first time Harris and Obama have campaigned together. Harris is slated to appear with Michelle Obama on Saturday in Michigan, one of seven swing states expected to decide the winner.

The latest polls in Georgia show Trump with a slight lead, but Harris campaign officials say they remain confident the state, along with its neighbour North Carolina, are still in play next month.

President Joe Biden pulled off a surprise victory in Georgia in 2020, and Democrats won two hard-fought Senate seats there that gave them control of both houses in Congress for the first half of his term.

Some 1.9 million residents have already cast their ballot in Georgia, according to the secretary of state’s office.

On Monday, Springsteen, 75, will also appear in Philadelphia with Obama.

The Harris campaign has dubbed the concert series “When we vote, we win”, as part of its strategy to make the most of early voting in the seven key battleground states. More concerts are expected to be announced in coming days.

In 2016, Springsteen played a three-song set at a rally in front of 20,000 people at Philadelphia’s Independence Hall for Democrat Hillary Clinton’s presidential campaign on the eve of the election. In 2008, he played a seven-song set for tens of thousands on the city’s Benjamin Franklin Parkway to urge people to register and vote for Obama.

Taylor Swift, Pink, Oprah Winfrey, George Clooney, Lizzo and many other celebrities have endorsed Harris and her running mate Tim Walz. Swift’s endorsement of Harris via an Instagram post this September has received more than 11 million likes.

Trump supporters from the entertainment world include musicians Ted Nugent, Kid Rock and Jason Aldean, wrestler Hulk Hogan, who spoke at this summer’s Republican National Convention, Ultimate Fighting Championship president Dana White, actor Dennis Quaid, and TV star Amber Rose.

-with AAP