WASHINGTON — When pro-Trump rioters burst into the Capitol on Jan. 6 demanding that lawmakers overturn the results of the presidential election, Representative Liz Cheney’s first thought as she stood on the House floor was that the attack was her own party’s doing.

As Ms. Cheney, a Wyoming Republican, and other lawmakers rushed to evacuate the chamber, Representative Jim Jordan, Republican of Ohio and a close ally of President Donald J. Trump’s, tried to help her move to safety. She smacked his hand away.

“Get away from me,” Ms. Cheney told him, adding that she blamed him for what was unfolding.

Hours later, as she hid in a secure location with other lawmakers while the Capitol was still under siege, she surprised a Democratic congressman who told her that it was crucial for lawmakers to quickly return to the House chamber to certify the election results.

“Yeah,” she responded. “And impeach the son of a bitch,” she added, referring to Mr. Trump.

Ms. Cheney’s reaction on Jan. 6 marked the culmination of a remarkable arc for the daughter of a prominent conservative family, from one of the most powerful leaders in her party to one of its most vocal critics, and a reviled foe of its de facto leader.

She has been unrepentant in continuing to blame Mr. Trump for stoking the attack, and her Republican colleagues for following his lead by spreading the lie of a stolen election. That stance has left her marginalized by her party, with her colleagues ousting her from her leadership position and seeking to purge her from the House by boosting a MAGA-styled primary challenger at home in Wyoming.

Now, from her perch as the vice chairwoman of the committee investigating the attack, Ms. Cheney is leading the charge to hold Mr. Trump to account for his efforts to overturn the election. On Thursday night, she takes center stage at the first in a series of six prime-time hearings this month to lay out the panel’s findings, with a high-profile role questioning witnesses and laying out the stakes of the riot.

“We face a threat we have never faced before — a former president attempting to unravel our constitutional republic,” Ms. Cheney said last month as she received the Profile In Courage Award from the John F. Kennedy Library Foundation.

“At this moment we must all summon the courage to stand against that,” she continued. “The question for every one of us is in this time of testing, will we do our duty? Will we defend our Constitution? Will we stand for truth? Will we put duty to our oath above partisan politics? Or will we look away from danger, ignore the threat, embrace the lies, and enable the liar?”

On Thursday, Ms. Cheney spent much of the day polishing her opening remarks, tapping away on her laptop in her suite in the Cannon House Office Building, a floor above the sprawling, chandelier-topped hearing room where she was to speak before a nationally-televised audience. The lawmaker wrote her own speech, aides said, in consultation with a small inner circle of advisers in her office and lawyers on the panel.

Her husband, Philip Perry, and one of her four children were to attend the evening hearing but former Vice President Dick Cheney and his wife, Lynne, remained in their suburban Virginia home. Ms. Cheney, however, speaks to her father every day, on the phone or in person, and discussed her remarks with him in the hours before Thursday’s hearing.

Ms. Cheney, who had been one of the most powerful Republicans in the House, was ejected from her leadership post last year for bluntly and repeatedly condemning Mr. Trump’s false election claims and blaming him for the riot.

Her blunt words about her party’s complicity in the riot were reported earlier in the book “I Alone Can Fix It: Donald J. Trump’s Catastrophic Final Year” by Washington Post reporters Carol Leonnig and Philip Rucker, and later confirmed by a congressional aide briefed on the exchange. Ms. Cheney’s earthy exhortation to impeach Mr. Trump was reported in the book “This Will Not Pass: Trump, Biden and the Battle for America’s Future,” by Jonathan Martin and Alexander Burns, two reporters for The New York Times.

Behind the scenes, Ms. Cheney is known to be one of the more engaged and aggressive questioners on the Jan. 6 panel. It was she who pressed to assemble a bipartisan team of former intelligence analysts and law enforcement specialists on the committee’s staff.

Ms. Cheney is one of just two Republicans to serve on the committee, alongside Representative Adam Kinzinger of Illinois, who has also openly condemned Mr. Trump. Both were selected by Speaker Nancy Pelosi, Democrat of California, after Republicans boycotted the committee in protest of her decision to bar two of their members from serving on it.

At nearly every turn since the riot, Mr. Trump and House G.O.P. leaders have sought to drive her out of the party, including by backing her Trump-endorsed primary challenger, Harriet Hageman. There are few Republicans the former president is more determined to beat than the Wyoming’s at-large House member, and polling shows that Ms. Cheney faces an uphill battle to keep her seat in a ruby-red state that still favors the former president.

“Nancy Pelosi loves her handpicked minion,” Ms. Hageman wrote on Twitter, sharing a news article about Ms. Cheney’s work on the Jan. 6 committee. “Wyoming? Not so much.”

The congresswoman finds herself in political jeopardy because, unlike some of the Republicans who have found themselves in Mr. Trump’s cross hairs, she has neither sought to repair her relationship with Mr. Trump nor ignored his criticism.

Instead, in taking a leadership role on the Jan. 6 panel, Ms. Cheney has elevated herself as perhaps the foremost critic of Mr. Trump in today’s Republican Party. She has said she views the assignment as the most important of her political career, and she often uses language borrowed from the criminal code — delivered in a characteristically blunt tone — to make clear she believes he faces criminal exposure.

“What Donald Trump did,” Ms. Cheney said, “was he really mobilized and motivated and summoned the mob. And the lie about the election was what lit the flame.”

In seemingly embracing political martyrdom, Ms. Cheney had invited speculation that she might not seek re-election — right up until the moment last month when she filed to do just that, shortly before the deadline.

Her broadsides against Mr. Trump have fueled speculation that, win or lose this summer in Wyoming, she will mount a long-shot campaign against the former president should he seek to reclaim the presidency.

In a video she posted as she filed for re-election last month, Ms. Cheney used the sort of lofty language to which she has often turned since breaking with her party last year, invoking her state’s distinctive sense of western honor — and perhaps previewing what she may offer voters in 2024.

“In Wyoming, we know what it means to ride for the brand,” Ms. Cheney said. “We live in the greatest nation God has ever created, and our brand is the United States Constitution.”

Ms. Cheney has made little secret of the fact that she considers her work on the Jan. 6 panel — and the political price she has paid for it — as historic.

“As you’re listening to some of my colleagues and others who think that the way to respond to this investigation is with politics and partisanship — those people are not acting in a way that is healthy for the country,” she said in an interview with The Dispatch earlier this week. “And if we really want to understand why Jan. 6 is a line that can never be crossed again, then we really do have to put the politics and the partisanship aside and say what happened.”

On Thursday, she was accompanied throughout the day by one of Mr. Cheney’s old friends, David Hume Kennerly, the famed photographer who forged a relationship with the future vice president when both served in President Gerald Ford’s White House, Mr. Cheney as chief of staff and Mr. Kennerly as official photographer.

Mr. Kennerly, who remains close with the family, has shown up, camera in hand, on other momentous days for Ms. Cheney, including last year when she was ousted from her leadership post by her Republican colleagues.

Leave a Reply

Your email address will not be published. Required fields are marked *