PHILADELPHIA – It wasn't even three weeks ago when Trish Callahan, a Democrat from Philadelphia, said her co-workers had to check to see if she was OK.
Then President Joe Biden withdrew from the election on July 21, and Vice President Kamala took his place as the Democratic nominee.
“I was preparing myself for the worst," said Callahan, 63, who works in fundraising at Temple University. "And as soon as Biden stepped down and endorsed Kamala, it was like I was resurrected from the dead. I donated. I volunteered."
It's been a night-and-day turnaround from the downward vibes of the Biden campaign to Harris' surge. And no scene captured the drastic shake-up as vividly as Harris' raucous rally in Philadelphia Tuesday night debuting her running-mate pick of Minnesota Gov. Tim Walz. Callahan was among the 14,000 supporters in attendance, the largest crowd of the still-young Harris campaign.
More:Why Kamala Harris chose Tim Walz over Josh Shapiro as her running mate
"It's been a bit of a whirlwind," Harris said after taking the stage, before informing the crowd that she officially secured the Democratic nomination Monday night after a virtual roll call vote of Democratic National Committee delegates.
"Now we have work to do. We need to move to the general election and win that. And we also need to level set," Harris added. "We are the underdogs in this race, but we have the momentum, and I know exactly what we are up against."
Waiting for Harris to come out, the boisterous crowd waved back and forth to rap songs and R&B classics like "Dancing in the Street" and "My Girl." When Harris and Walz finally arrived, the response was thunderous. It was nothing like the low-key Biden rallies of a month ago.
Harris ignited a roar from her fans when she told them that the United States won't return to the politics of former President Donald Trump.
"We're not going back!" the crowd chanted in response.
More:Kamala Harris energizes Democrats and shakes up presidential race. Can she keep this up?
Walz rips Trump, says he knows nothing about service
Harris has erased Trump's polling lead and raised a mountain of campaign cash since her candidacy began. Another $20 million came in Tuesday following her announcement of Walz as her running-mate, the campaign said.
In picking Walz, Harris opted for a messenger for the middle class in the Midwest over the electoral-map consideration that made Pennsylvania Gov. Josh Shapiro an appealing option. The Harris campaign thinks the plain-spoken, folksy Walz − who coined the "weird" attack line targeting Trump − can appeal to white working-class voters who have increasingly left the Democratic Party.
Introducing her running-mate, Harris repeatedly referred to "Coach Walz," a nod to his time as a high school social studies teacher and football coach. Walz is also a gun owner who supports gun restrictions, Harris noted, and a 24-year veteran of the National Guard.
“He's the kind of person who makes people feel like they belong, and then inspires them to dream big,” Harris said. “And that's the kind of vice president he will be, and that's the kind of vice president America deserves.”
More:Tim Walz debuts as Kamala Harris' VP pick at raucous Philly rally: Recap
Walz wasted little time in his remarks ripping into Trump, who he said "doesn't know the first thing about service." Of Trump's running mate JD Vance, Walz said, "I've got to tell you: I can't wait to debate the guy."
And in perhaps the biggest ovation of the night, Walz said: “Make no mistake, violent crime was up under Donald Trump. That's not even counting the crimes he committed."
The line was met with chants of, "Lock him up!"
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Harris, Walz and Shapiro present united front
The site of Philadelphia as the first in a series of battleground stops this week for the Harris-Walz ticket made for what could have been an awkward moment with Shapiro introducing the new duo. Shapiro, who was also in the running for Harris' running mate, was passed over for Walz.
But Shapiro instead made an impassioned case for Harris and Walz and sought to make clear he will work to deliver Harris Pennsylvania and its 19 electoral votes.
More:Tim Walz and the legacy of 'weird': Democrats embrace VP pick's one-word insult for MAGA
"I’m going to be working my tail off to make sure we make Kamala Harris and Tim Walz the next leaders of the United States of America,” Shapiro said, praising Walz's now-famous attack line.
“Tim Walz in his beautiful Midwestern, plain spoken way, he summed up JD Vance the best: He’s a weirdo,” Shapiro said, prompting the crowd to shout back, "He's a weirdo!"
The Jewish governor faced resistance from some progressives over his support for Israel in the Israel-Hamas war and his opposition to campus protesters calling for a cease-fire. He seemed to address the backlash in his remarks. "I lean on my family and I lean on my faith, which calls me to serve − and I am proud of my faith."
Despite the unmistakable enthusiasm on display Tuesday, some Harris supporters in the crowd confessed they knew little about Walz, who served in Congress before becoming governor, and had hoped Shapiro would be her pick.
“I actually don’t know anything about her running mate, but I will be doing some research so that I can get ready to talk to people about making sure that we get Harris,” said Terry Moragne-Macon, a 75-year-old retiree. "I'm looking forward to the first African American female president of the United States."
Other supporters appreciated the selection. Marc Seide, a 34-year-old web designer from Philadelphia, said he believes Walz "balances out" the ticket and believes Shapiro's opposition from progressives might have posed too many challenges.
"This is my first campaign event of the year, and I'm excited. I'm really excited to see how this goes," Seide said. "To go from Biden to Harris and to see that energy out here in the crowd − it's tremendous."
Reach Joey Garrison on X, formerly Twitter, @joeygarrison