Harris holds rally at Milwaukee arena where Trump accepted Republican nomination at RNC

Vice President Kamala Harris held a raucous rally Tuesday night in Milwaukee -- in the middle of the Democratic National Convention -- at the same arena where former President Donald Trump accepted the Republican nomination just a month ago.

A Harris campaign official said they weren't just doing a "victory lap" because of the momentum around the vice president -- instead choosing to hold a rally during the DNC because they still say they believe they are the "underdogs" and need to work hard to win over voters in battleground states such as Wisconsin, the official said.

These critical voters won't be in Chicago, and Harris needs to "meet them where they are," the official said.

"Good evening, Milwaukee!" Harris told the wildly cheering crowd. And hello to everyone joining us from exciting Chicago," Harris said to the DNC from the Wisconsin stage. "The delegates at the Democratic National Convention, well, they just completed their roll call and they have nominated Coach Walz and me to be the next vice president and president of the United States of America. And I thank everyone there and here for believing in what we can do together."

"We are so honored to be your nominees," Harris continued. "This is a people powered campaign, and together we will chart a new way forward. A future for freedom. Opportunity of optimism and faith. So, to everyone in Chicago and across America. Thank you. Thank you. Thank you," she said. "I'll see you in two days Chicago."

Milwaukee is "a place where we need to increase turnout and it's a good high-momentum, high-energy moment to dig in and talk to folks," the campaign official added before the rally. "We want to make this bigger than Chicago."

Harris' Tuesday event took place in the Fiserv Forum -- the location of the Republican National Convention's prime-time events and where Trump recently accepted his party's nomination to a packed house.

"If she can fill up that arena that can hold some 18,000 people -- that could get under Trump's skin," the campaign official said -- a reference to Trump's focus on crowd size.

In recent weeks, Trump has continued to make baseless claims that the Harris campaign pays for her crowd as his Democratic rival gains momentum with large-scale rallies.

Earlier this month, Trump falsely accused Harris' campaign of using artificial intelligence to fabricate crowds at a campaign rally in Michigan. A Harris campaign official told ABC News that the photo Trump called into question was taken by a Harris campaign staffer and that it was "not modified by AI in any way."

Harris' visit to Wisconsin comes after she spoke at the DNC briefly on Monday night. She is set to speak again at the convention on Thursday night where she will accept the party's nomination. Her husband, second gentleman Doug Emhoff is set to speak at the convention Tuesday night ahead of keynote speakers former President Barack Obama and former first lady Michelle Obama.

Democratic voters in the area said Harris needs to frequently visit Wisconsin to win the crucial battleground state. In 2020, President Joe Biden beat Trump by a narrow margin; in 2016, Trump won the state by an extremely narrow margin of about 22,700 votes over Hillary Clinton -- less than 1%.

Democratic voters noted that Harris is already doing more than Clinton in 2016, when the former secretary of state did not visit Wisconsin during the general election.

"The last time I felt this much excitement was when Obama ran," said Wisconsin resident Shannon Mattner, who is planning to attend Harris' rally. "We just feel like there's more hope now."

Daniel Barfouth, a union member from Wisconsin set to attend the rally, says he supports Harris because of her position on unions.

"I like what she has to say about unions. I like how the unions endorsed her," Barfouth said.

Barfourth drew a sharp contrast between Harris and Trump: "He talks about chaos. He doesn't talk about hope, connection or anything about love. He talks about tearing everything down."

Asked what Harris needs to do to win Wisconsin, Barfourth said that Harris needs to continue "putting herself out there as a normal person like everyone else: 'I'm one of you'. Trump isn't one of us. He was born with a silver spoon with his mouth. He hasn't had to suffer for anything."