(AP) — Republican Rep. Liz Cheney on Thursday endorsed and plans to campaign for Rep. Elissa Slotkin of Michigan, the first time that the critic of former President Donald Trump has crossed party lines to formally support a Democrat.

Cheney, who lost her Wyoming GOP primary, announced her support for the two-term House member from Holly, Michigan, in a statement by the Slotkin campaign that notes she plans to headline a campaign event with Slotkin in the Lansing-area district next Tuesday.

Slotkin is competing against Republican state Sen. Tom Barrett in Michigan’s 7th Congressional District. Their race is considered a toss-up by both sides and one of the Republicans’ chief targets in their campaign to win the House majority on Nov. 8.

Cheney and Slotkin serve on the House Armed Services Committee, but their shared background in the federal government goes back further. Cheney worked in the State Department before launching her political career, as did Slotkin, who worked in the CIA and the Defense Department as well.

Both have been vocal critics of House Republicans who have sought to downplay the siege of the U.S. Capitol on Jan. 6, 2021. Cheney is vice chair of the House Jan. 6 committee, which recently issued a subpoena for Trump to testify.

“I have come to know Elissa as a good and honorable public servant,” Cheney said in a statement included in the Slotkin campaign’s announcement. “While Elissa and I have our policy disagreements, at a time when our nation is facing threats at home and abroad, we need serious, responsible, substantive members like Elissa in Congress.”

Slotkin’s challenger was among a group of Michigan Republican state lawmakers who met with Trump in Washington after the 2020 election and later signed a letter asking the joint session of Congress to delay certifying the results.

Cheney has recently spoken out against Republican candidates who subscribe to Trump’s disproven claim that he was denied a second term as the result of widespread voter fraud. For instance, she has said Arizona GOP nominee for governor Kari Lake poses “a huge risk for democracy” in light of the candidate’s statement that she would refuse to certify election results she opposes.

For her part, Slotkin was an early and vocal proponent of the select committee’s formation.

Cheney’s role in the investigation into the violent breach of the Capitol and her unsparing criticism of Trump, a fellow Republican whom she described as “clearly unfit for future office,” cost her reelection to Wyoming’s at-large House seat. After her defeat in the August primary, she said she was considering a 2024 presidential campaign, which Trump is also expected to wage.

Though it’s unclear how the Jan. 6 attack will be reflected in the midterm voting, an Associated Press-NORC Center for Public Affairs Research poll this month found only 9% of U.S. adults think democracy is working “extremely” well or “very well” while 52% say it’s not working well.

The AP-NORC poll also found a large segment of Republicans, 58%, still believe Democrat Joe Biden’s presidential election wasn’t legitimate. That’s down slightly from 66% in July 2021. Exhaustive reviews in key states upheld Biden’s win, while judges — including some appointed by Trump — dismissed numerous lawsuits challenging the outcome. Trump’s own attorney general, William Barr, called the claims bogus.

“At a moment when the very heart of our democracy is being challenged, Rep. Cheney’s voice has been critical,” Slotkin said in the campaign press release. “Rep. Cheney has shown tremendous leadership over the last two years, and while we certainly don’t agree on every issue, I look forward to welcoming her to Michigan’s 7th district next week.”

As of two weeks ago, Michigan’s 7th District was the most expensive House race in the country, according to AdImpact, a nonpartisan political media tracking company. The two campaigns and outside groups had combined to spend $27 million.

Biden received more votes than Trump in the district in 2020 by less than 1 percentage point.

© Copyright 2022 Associated Press. All rights reserved.