STORY: Cheney, a commanding presence on the congressional panel investigating the Jan. 6, 2021, U.S. Capitol riot by Trump supporters, warned against descending into vitriolic partisan attacks that could tear the political fabric of the country apart and urged her audience to rise above politics."My fellow Americans, we stand at the edge of an abyss, and we must pull back," the 55-year-old daughter of former Vice President Dick Cheney said in a speech at the Ronald Reagan Presidential Library in Simi Valley, California."As the full picture is coming into view with the January 6 committee, it has become clear that the efforts Donald Trump oversaw and engaged in were even more chilling and more threatening than we could have imagined," Cheney said."We have to choose, because Republicans cannot both be loyal to Donald Trump and be loyal to the Constitution," she said. "We must not elect people who are more loyal to themselves, or to power, than they are to our Constitution."By opposing Trump, Cheney has become a pariah in a Republican Party that readily accommodates conservative firebrands like Marjorie Taylor Greene and Lauren Boebert, both staunch Trump allies.After being ousted from party leadership in the U.S. House of Representatives, censured by the Republican National Committee and no longer recognized by her state party, Cheney is facing a showdown against Trump in an Aug. 16 Republican primary in her home state of Wyoming.Trump has made her a main target of his revenge campaign against his perceived Republican enemies and she is trailing Trump-endorsed Republican challenger Harriet Hageman in polling.In a speech punctuated by cheers and applause, Cheney praised the bravery of former White House aide Cassidy Hutchinson, who testified at a public hearing on Tuesday that Trump knew the crowd of supporters he had summoned to Washington was armed with weapons including assault-style rifles when he urged them to march on the Capitol and sought unsuccessfully to join them.The mob stormed the Capitol in an attempt to stop Congress from certifying Democratic President Joe Biden's victory over Trump."Her superiors - men, many years older, a number of them - are hiding behind executive privilege, anonymity and intimidation. But her bravery and her patriotism yesterday were awesome to behold," Cheney said.