The former representative, vice chairwoman of the House January 6 Committee, and eldest daughter of America’s 46th vice president, Elizabeth Cheney, will vote for Vice President Harris in the November election, she announced in North Carolina on Wednesday. She says President Trump represents an existential threat to American democracy that cannot be stomached. 

Ms. Cheney was never likely to vote for Trump, given her years-long feud with the former president after the January 6 Capitol riot. The night before the vote on Trump’s second impeachment, she said that there has “never been a greater betrayal by a President of the United States of his office and his oath to the Constitution.”

Appearing at Duke University’s school of public policy, she reiterated her criticisms. 

“As a conservative, as someone who believes in and cares about the Constitution, I have thought deeply about this, and because of the danger that Donald Trump poses — not only am I not voting for Donald Trump — but I will be voting for Kamala Harris,” Ms. Cheney announced. 

She said at the event that “because we are here in North Carolina,” it was important to mention that it is not acceptable to write in a random individual’s name, or to vote for a third party. It is a binary choice, she warned. 

Ms. Cheney — the daughter of Vice President Cheney who, like her father — served Wyoming in Congress, was a staunch supporter of Trump until the January 6 Capitol attack. She rose to the position of Republican conference vice chairwoman, the third-highest position in the party’s House caucus. She was ousted from her position in May 2021 after conservatives revolted for her vote to impeach Trump after the Capitol riot. 

She was a top target of the former president when he went on a revenge tour against Ms. Cheney and the nine other House Republicans who voted to impeach him in the wake of January 6. Of the ten members who voted for those articles, just two are still serving as representatives, with one member, Congressman Dan Newhouse, at risk of losing his seat this year. 

Anti-Trump Republicans were featured prominently at this year’s Democratic National Convention, including one of Trump’s press secretaries, a homeland security advisor to Vice President Pence, and a Georgia lieutenant governor who faced death threats after Trump tried to overturn the state’s 2020 presidential election results. 

Neither a spokesman for Trump nor a spokesman for Ms. Harris immediately responded to requests for comment. 

It is not inconceivable that Ms. Cheney could hit the trail for Ms. Harris before the November election. In 2022, she campaign for at least one Democrat, Congresswoman Elissa Slotkin, in Michigan, saying she was a serious legislator who was better for America than her Trump-backed challenger.