GILLETTE, Wyo. (AP) — A retired U.S. Army colonel from California says he will challenge Liz Cheney in next year’s Republican U.S. House primary in Wyoming.

Denton Knapp, of Trabuco Canyon, California, said he plans to move back to Gillette, where he graduated from high school in 1983, the Gillette News Record reported Monday.

Five Republicans as of Monday had filed paperwork with the Federal Election Commission stating their intent to run against Cheney in 2022.

The list didn’t include Knapp yet but has been growing amid Republican discontent with Cheney for continuing to dispute former President Donald Trump’s unsubstantiated claim that vote fraud cost him re-election.

Cheney was among 10 Republican representatives who voted to impeach Trump over the deadly insurrection at the Capitol on Jan. 6. She has called her impeachment vote an act of conscience in defense of democracy and the Constitution.

Cheney faces a likely House GOP vote this week to remove her as conference chair, the chamber’s third-ranking Republican leadership post.

“What’s missing right now is trust in our elected officials,” Knapp said. “Wyomingites expected Cheney to vote a certain way and she didn’t. As a result, she’s going through consequences.”

A West Point graduate, Knapp served in the Army from 1987-2017, with service in countries including Iraq, Afghanistan, Jordan, Saudi Arabia and Kuwait. Most recently he has led the Tierney Center for Veteran Services at Goodwill of Orange County, according to his resume online.

Other Republicans running against Cheney include Cheyenne attorney and businessman Darin Smith, who announced his campaign Friday; state Sen. Anthony Bouchard, of Cheyenne; and state Rep. Chuck Gray, of Casper.

The race already is shaping up as one of the toughest of Cheney’s career. Cheney decisively won a nine-way GOP primary in 2016 and won Wyoming’s lone House seat by wide margins in 2016, 2018 and 2020.