Ripon, Wisconsin - Kamala Harris campaigned Thursday with Liz Cheney, a high-profile Republican opponent of Donald Trump who urged Americans to reject the ex-president's "depraved cruelty" and elect his rival.

Harris was joined onstage in the swing state of Wisconsin by the former congresswoman as the daughter of former Vice President Dick Cheney – an architect of the disastrous US invasion of Iraq – pleaded with moderate Republicans and independents to put patriotism over partisanship.

With just 33 days left in the extraordinary 2024 campaign, Harris "is standing in the breach in a critical moment in our nation's history," Cheney told the crowd in Ripon, the symbolic birthplace of the Republican Party in 1854.

"I ask you to stand in truth, to reject the depraved cruelty of Donald Trump. And I ask you instead to help us elect Kamala Harris for president," she said, to loud cheers and chants of "Thank you, Liz!"

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Calling Cheney a "true patriot," Harris thanked the Republican for her courage and "the conviction to speak truth," before also controversially expressing gratitude to her father for "his support and what he has done to serve our country."

Harris used her Wisconsin rally to reach out to Republicans who Democrats hope are turned off by Trump's extreme rhetoric on subjects ranging from abortion to migration and democracy.

She reminded Americans how Trump "recklessly tramples on our democratic values" and would likely do so again from the Oval Office should he win.

Liz Cheney was one of only 10 Republicans to vote to impeach Trump over the attacks on the Capitol by Trump supporters. She was thrown out of House Republican leadership for her opposition to Trump.

Hours before the pair took the stage, Trump rallied supporters in another closely-fought Midwestern battleground, Michigan, where he reprised his big lie of election fraud that led to the deadly violence.

His appearance came after the unsealing Wednesday of a bombshell filing in his prosecution for an alleged criminal plot to subvert the 2020 election, which argued that he had no presidential immunity for the "private criminal effort" and provided new evidence of his alleged misconduct.

"We did great in 2016 – a lot of people don't know. We did much better in 2020 – we won. We won, we did win. It was a rigged election," Trump said of his seven-million-vote defeat to Joe Biden in a now-familiar refrain.

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Trump also repeatedly misled his audience about the Biden administration's response to Hurricane Helene, which has devastated parts of the southeast, misrepresented migrant crime statistics, and questioned the mental health of Harris and two senior Democratic lawmakers.

The 78-year-old was delivering his remarks in the rust-belt Michigan county of Saginaw that he won in 2016 and then narrowly lost to Joe Biden in 2020.

Harris has narrow leads in polls in Wisconsin and Michigan, but both candidates know that all the swing states could go either way and are hitting them relentlessly in the home stretch.