Former Rep. Fred Upton, one of the 10 House Republicans who voted to impeach then-President Donald Trump on the heels of the Jan. 6, 2021 Capitol riot, has announced that he voted for Vice President Kamala Harris in the 2024 presidential contest.

Upton noted that he was "proud" to declare that he had already cast his vote for Harris.

He said that he had never previously voted for a Democratic presidential candidate and had never thought he would.

MORE THAN 100 FORMER GOP OFFICIALS FROM PAST ADMINISTRATIONS PUBLICLY ENDORSE HARRIS OVER TRUMP

Then-Rep. Fred Upton in 2021

Rep. Fred Upton (R-Mich.) dons a face mask with the word "DIGNITY" printed on it before a news conference about immigration outside the U.S. Capitol on March 17, 2021, in Washington, D.C. (Chip Somodevilla/Getty Images)

Upton asserted that Trump has repeatedly demonstrated that he is "unfit to serve as commander-in-chief."

While the former lawmaker said that he does not agree with Harris on all policies, he said that Harris is committed to Americans' best interests.

"I invite every single person across the country, Republican or Democrat, to stand up against the hate and chaos of Donald Trump, and vote for Harris as the next President of the United States," he declared.

HARRIS ACCUSES TRUMP OF EMBRACING ‘DIVISION AND EXTREMISM’ FOR PAST DECADE

Then-Rep. Fred Upton in 2020

Representative Fred Upton, a Republican from Michigan, center, speaks during a news conference with the Problem Solvers Caucus outside the U.S. Capitol in Washington, D.C., on Dec. 3, 2020. (Stefani Reynolds/Bloomberg via Getty Images)

Former Reps. Liz Cheney and Adam Kinzinger, the two Republicans who served on the House Select Committee established to investigate the Jan. 6 episode, have both been supporting Harris in the 2024 contest. And like Upton, they also voted to impeach Trump in 2021. 

Trump has blasted Cheney on social media as "Crazed Warhawk Liz Cheney" and "a low IQ War Hawk."

HARRIS AND TOP ANTI-TRUMP REPUBLICAN CHENEY TEAM UP IN BATTLEGROUND BLITZ

Then-Reps. Liz Cheney and Adam Kinzinger in 2022

U.S. Rep Adam Kinzinger (R-Ill.) (R) delivers remarks alongside Rep. Liz Cheney (R-Wyo.), Vice Chairwoman of the House Select Committee to Investigate the January 6th Attack on the U.S. Capitol during a hearing on the Jan. 6th investigation in the Cannon House Office Building on Oct. 13, 2022, in Washington, D.C.  (Drew Angerer/Getty Images)

CLICK TO GET THE FOX NEWS APP

Upton served in Congress for more than three decades, spanning from early 1987 to early 2023. He did not run in 2022.