Republican Liz Cheney has lost her Wyoming seat in Congress to a Trump-backed candidate from her own party.
She conceded defeat to Harriet Hageman, whose candidacy has been endorsed by the former president in the Republican primary.
Ms Cheney, 56, has been one of the most outspoken Trump critics in the Republican party and was one of 10 Republicans who voted to impeach Mr Trump in 2021 following the 6 January Capitol riots.
Meanwhile Ms Hageman has backed his assertion that the 2020 election was stolen.
Observers say Ms Cheney’s loss indicates that Mr Trump still has a grip on the Republican Party.
Speaking after the polls closed, Ms Cheney said she could have “easily” won the primary vote again, if she chose to support the former president.
“It’s a path I could not and would not take,” she added.
Ms Cheney spoke at length about the Capitol riots, calling it a “tragic chapter” and added that no candidate should support “election deniers”.
She then took aim at Mr Trump over his reaction to the FBI search of his Florida Mar-a-Lago estate.
Most of the candidates Mr Trump has backed this election season have triumphed in a sign, his supporters say, of his continued sway over the party. During the 2020 campaign, Mr Trump won the largest margin in Wyoming.
It comes amid speculation over whether the former president will run for office again in 2024.
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Ms Cheney, a three-term conservative congresswoman, used her campaign to keep attention on Mr Trump’s actions around the riot, and his continued false claims about fraud in the 2020 election, in a bid to persuade fellow Republicans the former president is a threat to democracy.
While her congressional voting record supports the former president’s agenda, Ms Cheney’s criticism of Mr Trump has pushed away many Wyoming Republicans.
Four of the 10 Republicans who voted to impeach Mr Trump opted to retire, three have already lost primaries, and two survived primaries.