Former congresswoman Liz Cheney, one of Donald Trump’s fiercest Republican antagonists, will join Democrat Kamala Harris at a campaign event in Wisconsin on Thursday aimed at reaching out to moderate voters.

Ms Cheney was the top Republican on the House committee that investigated the January 6 2021 attack on the Capitol in Washington, earning former president Trump’s disdain and effectively exiling herself from her own party.

Ms Cheney lost her House seat to a Trump-endorsed candidate two years ago and she endorsed Ms Harris, the Democratic nominee, last month.

The two women will appear together in a historic white schoolhouse in Ripon, where a series of meetings held in 1854 to oppose slavery’s expansion led to the birth of the Republican Party.

Ms Harris is opening a two-day stay in Wisconsin and Michigan, and Mr Trump himself will be in Michigan on Thursday as the two candidates grapple for wins in the so-called “blue wall” battleground states, which also include Pennsylvania.

Ms Harris’s visit to Wisconsin comes one day after a federal judge unsealed a 165-page court filing outlining prosecutors’ case against Mr Trump for his attempt to overturn his 2020 election defeat. Mr Trump has pleaded not guilty to charges of conspiracy and obstruction.

Dick Cheney, Liz’s father, was vice president under George W Bush.

But now both Cheneys are backing Ms Harris, part of a cadre of current and former Republican officials who have broken with the vast majority of their party, which remains in Mr Trump’s corner.

Ms Harris wants to portray her candidacy as a patriotic choice for independent and conservative voters who were disturbed by Mr Trump’s unwillingness to cede power. Mr Trump continues to deny his defeat with false claims of voter fraud.

On Friday, Ms Harris will hold a campaign rally in Flint, Michigan, continuing her tour of so-called “blue wall” states that have been critical to Democratic victories in presidential races. Mr Trump won Pennsylvania, Wisconsin and Michigan in 2016, and Joe Biden won them in 2020.

On Thursday, Mr Trump will hold a rally in Saginaw County, a bellwether in the centre of the state.

The Republican candidate has ramped up his focus on Michigan, holding two rallies there less than a week ago. In 2020, Mr Biden’s win in Saginaw County by a slim 303 votes contributed to his victory in the state.