Democrats have long attracted celebrity support, but no one has deployed them quite like this

For Harris' campaign, this scene in a Milwaukee-area event hall was far from an outlier. In the closing stretch of this campaign, a typical rally for the vice president features not just local officials and down ballot Democrats but an array of musicians and performers, from global A-listers and established favorites to buzzy up-and-coming artists.

The biggest names have been called in not to play the hits but to make the case for Harris. In Wisconsin on Friday, for instance, Cardi B took the stage to her breakout "Bodak Yellow," but took the mic to explain why she was supporting Harris.

"I wasn't gonna vote," the New York hip-hop star told supporters, who held hundreds of phones in the air, recording her speech. "But Kamala Harris joining the race, she changed my mind completely."

Democrats have long called in celebrities to juice the energy and appeal of their campaigns. But perhaps no candidate has done it as extensively — or, more importantly, as intentionally as Harris has against Donald Trump.

"They've been very strategic," said Karen Finney, a Democratic strategist who served as Hillary Clinton's 2016 spokesperson and who is helping to craft the pro-Harris camp's strategy for cultivating social media influencers.

Drawing on a long list of notables who are both alarmed by a Trump return and excited by the prospect of a Black female president, the Harris team has deployed figures with specific appeal to components of the wide-ranging Democratic political coalition.

The rally in the Milwaukee area — a hub of Black votes in the key swing state — had emerging hip-hop artists on hand. Two days before, Harris rallied to the west, in the college town of Madison, where students packed an arena and heard folk rock band Mumford and Sons as well as singer Gracie Abrams, a Gen-Z favorite who recently opened for Taylor Swift on tour.

Other recent Harris rallies have seemed like mini-festivals, from an Atlanta event on Saturday featuring rap legend 2 Chainz to a Houston event where Willie Nelson performed and Beyonce spoke.

The overall strategy is less to pack arenas and more to generate moments and messages that reach the right voters — one tailored to the atomized environment of social media, where influencers and famous figures are increasingly viewed as legitimate news sources.

Snippets of star-studded rallies can spread organically through attendees or media sharing their own video. The more powerful weapon is when Harris's "special guests" post about their campaign activity to platforms where they have massive followings.

Cardi B, for instance, posted a photo of her all-white outfit for the Wisconsin rally, and a message, to her 165 million Instagram followers. "We have to make a change on Tuesday and I know she's the one to take us there," she wrote.

In the closing weeks of a fiercely contested race, gaining even a small edge is imperative for each campaign. If a celebrity speech or performance can generate buzz that leads to just a few thousand extra votes, the impact on the outcome of the race could be disproportionately high.

Given Hollywood and the entertainment industry's liberal bent, Trump was always going to have a hard time matching Harris's star wattage. A familiar and small roster of conservative entertainers, like Jon Voight and Kid Rock, remain the most prominent names routinely broadcasting their support for Trump.

In 2024, Trump's team has sought to expand the tent, elevating rappers, like Waka Flocka Flame, and athletes, like former Pittsburgh Steelers player Le'Veon Bell, to underscore what they hope is the former president's increased appeal to Black voters. But cracks have emerged in that effort: rapper Sexyy Red, who endorsed Trump last year, revealed this week she voted for Harris because of reproductive rights — though she framed the issue more coarsely in a social media post.

For Harris, the star-studded rallies are just one way stars are being used. On Saturday, the pop singer Olivia Rodrigo posted an Instagram video of her conversation with Hadley Duvall, a childhood rape survivor from Kentucky who has become a powerful advocate for abortion rights.

"Stories like Hadley's are exactly why this election is so important," Rodrigo wrote in the post to her over 38 million followers, urging followers to vote for Harris and directing them to a website where they can make a plan to vote.

Harris, of course, has already landed the most prized celebrity there is: Taylor Swift. The pop megastar has not yet performed or spoken on behalf of the Democratic ticket, but her endorsement — posted to Instagram after the candidates' September debate — reportedly steered over 400,000 people to a voter registration website within 24 hours. Harris also attracted the support of Puerto Rican superstar Bad Bunny, who — after insulting remarks about Puerto Rico were made at a Trump rally — posted a video of Harris addressing Puerto Rican voters to his 45.7 million followers.

The sheer number of entry points the Harris campaign has to leverage celebrities to reach voters is part of what makes the 2024 campaign unique compared to even 2020 or 2016, said Finney.

"There are a lot of different ways that people are touched," she said. "It can be through social media, you have something in your feed, or you heard it on the radio, or you're reading something online and you heard Cardi B was there, and you say, 'I'll check that out.'"

But, Finney said, competing in a busy information landscape is not easy. "It has also added to the challenge," she said. "You want to stop people from scrolling for a minute — not even a whole minute, 15 seconds."

In person, most people on hand at these rallies aren't braving the lines and packed parking lots in order to catch a free show, however. The main draw remains Harris, as well as top surrogates like former first lady Michelle Obama, who spoke on Saturday to a packed crowd in the Philadelphia suburbs on Sunday, who also heard from Grammy-winning artist Alicia Keys.

Given how immensely popular the former first lady is, some attendees treated both women like celebrities. As guests streamed out of the Norristown Area High School gym, one young woman exclaimed, "Alicia Keys signed my hat! I shook Michelle Obama's hand!"

In Wisconsin, many attendees told the Globe they were excited to hear GloRilla — and another opener, Flo Milli — as well as Cardi B. But many had already registered for the rally before the musical guests were even announced. Hannah Castillo, from the suburb of Menomonee Falls, said she didn't know until the day before about the performers and had to ask her teenager, "who is GloRilla?"

During a lull in the action, two women — Kimberly James-Jones and Schemata Henderson, both from Milwaukee — were still waiting for who they had really come to see.

"Even without the free concert, I'd be here," said Henderson. "It's really about seeing her speak in this moment."

Still, the star power was hard to ignore. The upbeat and energetic performances, James-Jones said, were "the cherry on top of the sundae."

Sam Brodey can be reached at sam.brodey@globe.com. Follow him @sambrodey.