Moments after taking the stage for their first rally together Tuesday, Minnesota Gov. Tim Walz thanked Vice President Kamala Harris for putting her trust in him as her new running mate. But, he added, “maybe more so, thank you for bringing back the joy.”

Just a month ago, Democrats were feeling less than joyful as they agonized over the fate of President Joe Biden’s reelection campaign after a bad debate performance. His decision to eventually drop out and back Harris as his replacement reinvigorated the party.

In his first day on the ticket, Walz appeared to give Democrats another jolt of energy.

His selection drew plaudits from elected officials along the ideological spectrum ranging from Sen. Joe Manchin III (I-W.Va.) to Rep. Alexandria Ocasio-Cortez (D-N.Y.). But it also gave rank-and-file Democrats another fresh face to get excited about on social media and the campaign trail, with his Midwestern folksiness and happy-warrior demeanor.

Olivia Julianna, a 21-year-old digital strategist and content creator from Houston, scored a front-row seat at the Philadelphia rally, and though Walz was not her first choice for running mate, she said she left “completely sold.”

“He just has this raw sense of humility and humanity that I feel like you don’t see from politicians very often,” said Julianna, who often posts about politics to her nearly 375,000 X followers. “He comes across as very authentic and genuine. And I think that kind of energy and authenticity will inspire hope” across the political spectrum.

It remains to be seen if the energy can shake up the race, where Harris and former president Donald Trump are still polling closely in battleground states.

Trump, during an appearance Wednesday on Fox News, sought to portray Walz as “a very, very liberal man” and “a shocking pick” — echoing lines that other Republicans have embraced in trying to discredit Harris’s selection.

“I could not be more thrilled,” Trump said, suggesting Harris had passed over better alternatives.

Vice-presidential candidates rarely fundamentally alter the race. And in politics, the best day for any candidate is often considered their first day, before the opposition’s attacks set in. But for now, Democrats see at least an intangible benefit to the fresh enthusiasm.

“Fun campaigns are winning campaigns,” Democratic operative Caitlin Legacki wrote on X. “And this is a very, very fun campaign.”

That has been especially true on social media. From Harris’s announcement of Walz until 5 p.m. Tuesday, posts about Walz on TikTok racked up over 43 million collective views. Sixty-nine percent of those views came from videos produced by progressive content creators and 28 percent came from politically independent creators, according to CredoIQ, a social media analytics firm.

The Harris campaign has helped stoke the online fervor, selling a camouflage “Walz Harris” hat after some supporters suggested it as a play on a similar-looking hat made popular by singer Chappell Roan. A campaign official said the product sold out in a half-hour.

“Walz has gone from virtual unknown to household name overnight,” said Brendan Gahan, chief executive officer and co-founder of Creator Authority, a digital and influencer marketing agency. “This surge in popularity isn’t just driven by political pundits; he’s having a viral moment.”

Harris had a similar experience after Biden withdrew. Social media filled with celebratory memes referencing her May 2023 remarks recalling how her mother would question young people if they think they “just fell out of a coconut tree.” The singer Charli XCX gave Harris another boost online when she posted on X, “kamala IS brat,” referring to the singer’s term for a carefree lifestyle.

Harris’s devotees became “coconut-pilled.” And before long, advocates for her to pick the Minnesota governor were “Walz-pilled,” impressed with his down-to-earth appeal and liberal policy achievements in Minnesota, such as making school lunch free.

Harris leaned into Walz’s folksiness during their first rally together Tuesday in Philadelphia. As he laughed and applauded effusively alongside her, she repeatedly called him “Coach Walz” and noted how he also went by “Mr. Walz” when he taught high school students.

“And in 91 days, the nation will know Coach Walz by another name — vice president of the United States,” Harris said to big cheers.

Speaking after Harris, Walz offered no shortage of lighthearted moments. He shouted out to “old White guys” in the crowd, alluded to a baseless internet joke about Trump’s running mate, Sen. JD Vance (R-Ohio) — the crowd roared with laughter — and reprised the jab that helped make him a serious vice-presidential contender in the first place, calling the Republican ticket “just weird as hell.”

Julianna said Harris’s campaign has been smart to leverage all the online exuberance about Harris and Walz in a way that energizes highly engaged supporters but is still accessible to everyday voters.

“I think it’s just really, really brilliant,” said Julianna, who rose to prominence in 2022 after using online ridicule from Rep. Matt Gaetz (R-Fla.) to raise money for abortion access.

Lindsey Gamble, an online marketing and digital strategy consultant in Boston, also praised the Harris campaign for tapping into the online energy, saying she “has been really digital first throughout this campaign.”

“It’s like FOMO [Fear of Missing Out], when you see someone tweeting about [Walz] or posting about him, it’s sparking interest to dive deeper and learn more about him,” Gamble said.

The hours before the rally saw abundant jokes on social media about what some called his “Midwestern dad vibes.” Enthusiasts circulated a five-year-old video of him and his teenage daughter trying to record a message about the start of hands-free driving in Minnesota, bickering with one another while seated together in the front seat of a car.

“Tim Walz 100000% stands at his doorstep when it’s raining and says ‘we needed this,’” the prominent gun-control activist David Hogg said Tuesday on social media, spawning many other posts applying stereotypical dad behavior to Walz.

As Democrats celebrated, Republican sought to exploit what they argue are Walz’s weaknesses.

While some Republicans went after Walz directly, others also used his debut to question Harris’s judgment. Vance said it “just highlights how radical Kamala Harris is.”

“This is a person who listened to the Hamas wing of her own party in selecting a nominee,” Vance told reporters, referring to Harris’s decision to pass over Pennsylvania Gov. Josh Shapiro, whose Israel positions had drawn some liberal opposition.

Other Republicans took to social media to also criticize Harris’s decision to pass over Shapiro — and express surprise that she did not pick the popular governor of a swing state.

As Republicans started attacking Walz in dark terms — Trump said in an email to supporters that Walz will “unleash HELL ON EARTH” — some supporters responded with joyful past photos of the governor, including of him laughing heartily while holding a piglet.

“Coconut-pilled. Walz-pilled,” the former Barack Obama speechwriter Jon Favreau said on X as the news of Walz’s selection broke. “What else can the internet manifest for this election??”