Vice Chair Rep. Liz Cheney, R-Wyo., listens as the House select committee investigating the Jan. 6 attack on the U.S. Capitol holds its final meeting on Capitol Hill in Washington on December 19, 2022.
CNN  — 

Former Republican Rep. Liz Cheney said Tuesday that she’s committed to doing what’s necessary to stop former President Donald Trump from returning to the White House, as she continues to mull a third-party presidential run in 2024.

“There’s a huge amount of work to be done after this election cycle, whether it’s rebuilding the Republican Party – which increasingly looks like, you know, maybe an impossible task – or helping to begin a new party that’s very focused on what the Republican Party used to stand for before this cult of personality. But right now and in this election cycle, I’ll do whatever I have to do to make sure Donald Trump’s not elected,” she told CNN’s Anderson Cooper on “AC360.”

Cheney, an outspoken critic of Trump, said a third-party challenge in 2024 should be considered, but warned that uniting against the former president “can’t be a partisan issue.”

“We’re at a moment where the possibility of a third-party run is something we have to consider more than we ever have before because of the threat that Trump poses,” she said. “But I also think we have to ensure that at some point, we’re unified against him. It has to be a situation where we say, ‘I don’t care what your view is on this issue or that issue or whatever the big policy issue is. If you care about the Constitution and you’re going the defend it, we have to work and vote together for that.’”

The former Wyoming congresswoman and daughter of former Vice President Dick Cheney has floated the possibility of running for president against Trump on several occasions while promoting her new book “Oath and Honor: A Memoir and a Warning,” and told The Washington Post in recent days that she wouldn’t have considered a third-party run “several years ago,” but that things have changed.

On CNN Tuesday, Cheney offered a grim prediction of what a second Trump presidency could be like, insisting that he would pardon January 6 rioters, refuse to enforce court rulings, and that there wouldn’t be “some of the good people to stop him.” Currently elected Republicans, she told Cooper, “can’t be counted on to defend the Constitution.”

“A president who won’t enforce the law creates a situation where things just unravel. And he will have people around him who will help him do it,” she said.

Cheney issued a similar warning in her book.

“Trump has told us that he thinks the Constitution can and should be suspended when necessary, that what happened on Jan. 6 was justified, that in a second Trump presidency he would seek retribution,” she wrote in an excerpt. “The assumption that our institutions will protect themselves is purely wishful thinking by people who prefer to look the other way.”

Cheney lost her post in House Republican leadership and, ultimately, her seat in Congress after publicly rejecting for months Trump’s lie that he won the 2020 presidential election and voting to impeach him following the January 6, 2021, US Capitol attack. She played a prominent role in the House select committee’s investigation of the attack as the panel’s vice chair. Since leaving Congress earlier this year, she has remained a critical voice on the GOP’s future and Trump’s potential second White House term.

Throughout her book, Cheney detailed how she saw her Republican colleagues fall in line to support his claims of election fraud following the 2020 election. In one instance, Cheney recalls GOP members reluctantly signing their names on electoral vote objection sheets for the states Republicans were contesting.

“Among them was Republican Congressman Mark Green of Tennessee,” Cheney wrote. “As he moved down the line, signing his name to the pieces of paper, Green said sheepishly to no one in particular, ‘The things we do for the Orange Jesus.’” A spokesman for Green has denied that he made that comment.

The book ends with a call to action that Cheney says spans the political spectrum. “Every one of us – Republican, Democrat, Independent – must work and vote together to ensure that Donald Trump and those who have appeased, enabled, and collaborated with him are defeated,” she wrote.

Cheney has split with the Republican Party during previous elections.

Last year, 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, who had amplified Trump’s lies that the 2020 election was stolen. She also crossed party lines to stump for two moderate Democrats in competitive House races last year.

This story has been updated with additional developments.

CNN’s Ryan Brooks, Jamie Gangel, Jeremy Herb and Elizabeth Stuart contributed to this report.