GOP Rep. Liz Cheney said Americans will learn new details about what Trump was doing before, during and after the attack at the Capitol in his effort to remain in power despite his 2020 election loss.

"Over multiple months, Donald Trump oversaw and coordinated a sophisticated seven-part plan to overturn the presidential election and prevent the transfer of presidential power," she said.

The Wyoming Republican asserted Trump told his staff during the riot that it's what people "should be doing" and that he agreed with protesters urging violence against then-Vice President Mike Pence.

After the dust settled, Cheney said, Trump continued to ignore the statements from the Department of Justice, election officials and his own staff telling him the election result was legitimate.

"President Trump summoned the mob, assembled the mob and lit the flame of this attack," she said in her opening statement.

In his opening statement, Chairman Bennie Thompson -- looking directly at the camera -- called Jan. 6 an "attempt to undermine the will of the people" and "only the beginning of what became a sprawling multistep conspiracy aimed at overturning the presidential election."

"Trump was at the center of this conspiracy, and ultimately, Donald Trump, the president of the United States, spurred a mob of domestic enemies of the Constitution to march down Capitol and subvert American democracy," he said.

Thompson said the attack on the Capitol was "the culmination of an attempted coup" and a "brazen attempt ... to overthrow the government"

"The violence was no accident," he said. "It represents President Trump's last stand, his most desperate chance to halt the transfer of power."

Chairman Bennie Thompson has gaveled in the committee's first prime-time hearing intended to "remind you of the reality of what happened that day."

"But our work must do much more than just look backwards. Because our democracy remains in danger," Thompson will say in his opening statement, according to an excerpt released by the committee. "The conspiracy to thwart the will of the people is not over."

Americans will hear live testimony from a Capitol Police officer and documentarian who were on the scene of the attack and watch never-before-seen video footage in a rare congressional hearing made for television.

Rep. Liz Cheney, R-Wyo., vice chair of the select committee, was the first member to arrive on Capitol Hill through the member entrance, according to an NBC pool reporter.

Asked how she was feeling, Cheney said, "Good, thank you," as she walked inside.

Cheney and Rep. Adam Kinzinger, R-Ill., the only other House Republican to accept a seat on the panel, have faced relentless attacks from within their caucus for their participation. Cheney was removed from her No. 3 House GOP leadership post last year, and both were formally censured by the Republican National Committee for choosing to investigate what it controversially called "legitimate political discourse."