WATCH: Liz Cheney joins Harris rally at historic birthplace of the GOP in swing state Wisconsin

RIPON, Wisc. (AP) — Liz Cheney, one of Donald Trump’s fiercest Republican antagonists, rallied with Kamala Harris on Thursday at the site in Wisconsin where the modern Republican Party was born, as the Democratic vice president aimed to win over moderate voters and rattle the former president.

Watch the event in the player above.

The daughter of former Republican Vice President Dick Cheney, former Rep. Liz Cheney was the top GOP lawmaker on the House committee that investigated the Jan. 6, 2021, insurrection, earning Trump’s disdain and effectively exiling herself from her own party.

“Violence does not and must never determine who rules us. Voters do,” Cheney told the crowd as she recounted Trump refusing to act as he watched the violent attack on television. Someone in the crowd yelled “coward!” Others booed.

“He praised the rioters. He did not condemn them. That’s who Donald Trump is,” Cheney said.

She lost her Wyoming seat to a Trump-endorsed candidate two years ago and she endorsed Harris, the Democratic nominee, last month. The two women appeared together in Ripon, home to a white schoolhouse where a series of meetings held in 1854 to oppose slavery’s expansion led to the start of the Republican Party.

“I know that she loves our country, and I know she will be a president for all Americans” Cheney said of Harris. Noting that she herself remains conservative, Cheney said she was “honored to join her in this urgent cause.”

Instead of her usual “Harris-Walz” campaign signs, the stage was decorated with large signs that said “Country Over Party,” along with plenty of red, white and blue bunting.

Harris was opening a two-day trip to Wisconsin and Michigan, and Trump was in Michigan on Thursday as the two candidates grapple for wins in the “blue wall” battleground states, which also include Pennsylvania.

Meanwhile, President Joe Biden said Thursday that he wasn’t concerned about a Trump-Harris race coming down to the wire because “it always gets this close.”

“She’s gonna do fine,” Biden said of Harris to reporters on the South Lawn of the White House on his way to visit storm-ravaged Georgia and Florida. He added that Harris’ running mate, Minnesota Gov. Tim Walz, did well in his debate with Republican vice presidential nominee JD Vance during Tuesday’s debate in New York.

“The other guy lost the debate,” Biden said. “He misrepresented everything.”

Harris’ visit to Wisconsin comes one day after a federal judge unsealed a 165-page court filing outlining prosecutors’ case against Trump for his attempt to overturn his 2020 election defeat. Trump has pleaded not guilty to charges of conspiracy and obstruction.

Trump did not mention the document filed by special counsel Jack Smith or Cheney’s appearance with Harris during an 82-minute speech at a rally in Saginaw County, Michigan. In 2020, Democrat Biden won the bellwether county by a slim 303 votes, contributing to his victory in the state.

WATCH: What newly unsealed evidence reveals about Trump’s alleged actions on and before Jan. 6

As Trump spoke, his campaign announced he’ll appear in Georgia on Friday with Republican Gov. Brian Kemp. The two men have made peace after Trump in August unleashed a blistering attack on Kemp, whom he has faulted for not giving in to his efforts to overturn his loss in 2020.

As for Harris, it’s uncommon, to say the least, for a candidate to give a nod to the origins of the opposing party in the closing weeks of a presidential campaign. Not only that, the Cheney name was once anathema to Democrats who deplored Dick Cheney, Liz’s father, for his role as vice president under George W. Bush.

During the 2020 campaign, Liz Cheney criticized Harris as “a radical liberal” who “wants to recreate America in the image of what’s happening on the streets of Portland & Seattle,” a reference to unrest that took place in those cities after the murder of George Floyd.

But Jan. 6 was a turning point for Liz Cheney and her family. Both Cheneys are backing Harris, part of a cadre of current and former Republican officials who have broken with the vast majority of their party, which remains in Trump’s corner. Harris wants to portray her candidacy as a patriotic choice for independent and conservative voters who were disturbed by Trump’s unwillingness to cede power. Trump continues to deny his defeat with false claims of voter fraud.

Harris on Thursday also was endorsed by Cassidy Hutchinson, who was a young White House aide during Trump’s presidency and described during a hearing of Cheney’s Jan. 6 congressional committee how she grew disgusted by Trump’s refusal to stop the rioters that day. Harris’ campaign also began airing ads targeting Republicans, independents and former Trump voters in battleground states.

Cheney’s presence prompted some dissonance for Harris supporters in the audience, especially those that remember her father’s role as a Republican headliner.

Victor Romero, 46, said it was “a little weird” to be at an event with her.

“I still don’t like Liz Cheney’s politics. But I’m glad that she understands the Republican Party that currently exists is just for Trump.”

But for younger voters, they know Cheney primarily for standing up to Trump.

“She stuck to her morals,” said Kynaeda Gray, 22.

Harris on Friday will hold a campaign rally in Flint, Michigan, continuing her tour of states that have been critical to Democratic victories. Trump won Pennsylvania, Wisconsin and Michigan in 2016, and Biden won them in 2020.

Trump has ramped up his focus on Michigan, holding two rallies there less than a week ago before Thursday’s appearance in Saginaw.

Associated Press writer Joey Cappelletti in Saginaw, Michigan and Jonathan J. Cooper in Phoenix contributed to this report.