Republican former Rep. Liz Cheney will campaign with Vice President Kamala Harris in Wisconsin on Thursday, touting her endorsement of the Democratic presidential nominee in the crucial battleground state, a senior campaign official told CNN.

The campaign event marks the latest effort from the former Wyoming congresswoman to move undecided voters away from former President Donald Trump with less than five weeks until Election Day. Cheney, who previously told CNN she was committed to doing what was necessary to stop Trump from returning to the White House, endorsed Harris last month in North Carolina, another swing state.

“I think it is crucially important for people to recognize, not only is what I just said about the danger that Trump poses something that should prevent people from voting for him, but I don’t believe that we have the luxury of writing in candidates’ names, particularly in swing states,” Cheney said during remarks at Duke University in early September. She later said she expected to campaign against Trump in battleground states throughout the fall.

At the Thursday campaign event in Ripon – home to a schoolhouse known as the birthplace of the Republican Party – Harris will make a direct appeal to Republican and independent voters, according to the campaign official. She is expected to note the historical significance of Ripon and promise them that she will uphold the rule of law and the Constitution, even if they disagree with her on policy issues.

Cheney’s zealous opposition to Trump and his efforts to overturn the 2020 election – including her vote to impeach him – eventually led the House GOP to oust her as conference chair and replace her with a top Trump ally, New York Rep. Elise Stefanik. Cheney went on to serve as vice chair of the House select committee that investigated the January 6, 2021, attack on the US Capitol. She ultimately lost her seat in Congress in a 2022 primary to a Trump-backed challenger.

Cheney said in September that she had serious policy disagreements with Harris on a variety of issues but chose to support her because she feels that “those of us who believe in the defense of our democracy, in the defense of our Constitution, and the survival of our republic have a duty in this election cycle to come together to put those things above politics.”

A slew of Republicans have backed the vice president in her bid to defeat Trump and urged members of the GOP to cross party lines, including Cheney’s father, former Vice President Dick Cheney; former Illinois Rep. Adam Kinzinger; former Georgia Lt. Gov. Geoff Duncan; and former Arizona Sen. Jeff Flake.

Cheney has long tried to combat Trump’s influence in elections. In the 2022 midterms, the political action committee she started placed an ad buy urging Arizona voters to reject GOP gubernatorial nominee Kari Lake and Republican Secretary of State nominee Mark Finchem. She also crossed party lines to stump for two moderate Democrats in competitive House races that year.

Broader push to win over Republican voters

The campaign’s efforts to win over Republicans voters will extend beyond the Cheney event.

Thursday’s campaign stop will be the start of a host of other events over the coming days, meant to appeal to voters disenchanted with Trump and principally worried about defending the Constitution, according to a Harris campaign official. Other events will be held in Pennsylvania, Michigan, Arizona, Nevada, Georgia, North Carolina and Wisconsin.

Harris-Walz is spending significant money in this space as part of a more than seven figure paid media strategy, the campaign official said. While Trump’s team have former Democrats as surrogates, there is no organized “Democrats for Trump” equivalent.

Republicans for Harris’ outreach will also include a new economy-focused ad featuring a direct to camera testimonial from a two-time Trump voter on how Trump would make the economy worse for people like him, said the campaign official. The ad, “Has Our Backs,” first shared with CNN, is part of the campaign’s $370 million advertising reservations between Labor Day and Election Day and will run on digital platforms, including YouTube TV.

“We know that these are votes we need to earn, and we’re continuing to put in the work everyday to win over the millions of Republicans who are ready to turn the page on the chaos, extremism, and division of Donald Trump,” said Austin Weatherford, national Republican outreach director for the Harris-Walz campaign, in a statement.

Not all Democrats think this is the best strategy.

Georgia state Rep. Ruwa Romman, the first Muslim woman elected to the body, has been especially vocal on social media about the problems she views with the Harris team leaning into endorsements from prominent Republicans like Cheney.

“It feels like the campaign is still trying to run a Biden campaign, and it’s doing Harris a massive disservice,” she posted on X.

“Republicans are not gonna save us, and touting their endorsements is turning people off,” Romman said.

CNN’s Veronica Stracqualursi contributed to this report.