U.S. Rep. Mo Brooks (R-AL) makes an announcement in Huntsville, Alabama, U.S. March 22, 2021.
U.S. Rep. Mo Brooks (R-AL) makes an announcement in Huntsville, Alabama, U.S. March 22, 2021. Reuters / ELIJAH NOUVELAGE

Former President Donald Trump withdrew his endorsement of U.S. Senate Republican hopeful Mo Brooks' struggling campaign on Wednesday, dealing a crippling blow to the ambitions of one of his staunchest allies in the U.S. Congress.

In a statement underscoring the loyalty Trump demands, the Republican castigated Brooks - a hardline firebrand in the House of Representatives - for telling voters in Alabama that it was time to move on from the 2020 presidential election and Trump's false claims that it was stolen from him.

"Mo Brooks of Alabama made a horrible mistake recently when he went 'woke' and stated, referring to the 2020 Presidential Election Scam, 'Put that behind you, put that behind you'," Trump said in a statement. "Since he decided to go in another direction, so have I, and I am hereby withdrawing my Endorsement."

Brooks responded by accusing Trump of making unconstitutional demands to rescind the 2020 election results following their certification on Jan. 6, 2021, remove President Joe Biden and return Trump to the White House.

"I've told President Trump the truth knowing full well that it might cause President Trump to rescind his endorsement. But I took a sworn oath to defend and protect the U.S. Constitution. I honor my oath," Brooks said.

Brooks also showed no sign of withdrawing from the race, describing himself as "the only proven America First candidate" and predicting "the people of Alabama will see that on Election Day".Trump has endorsed dozens of candidates in 2022, in races ranging from state legislatures to the U.S. Senate, a list that has included both veteran officials and political newcomers.

He has endorsed primary challengers to nine incumbent congressional Republicans who voted to impeach him on a charge of inciting the U.S. Capitol riot of Jan. 6, 2021, or to convict him on that charge in a Senate trial that ultimately ended in his acquittal.

But Trump has had a mixed record. In Ohio, his endorsement of a primary challenger to U.S. Representative Anthony Gonzalez led the congressman to end his re-election bid.

Another endorsee, Republican Sean Parnell, suspended his Pennsylvania U.S. Senate campaign after losing a battle over the custody of his three children amid allegations of physical and verbal abuse of his estranged wife. The Army veteran was vying for the seat held by conservative Republican Senator Pat Toomey, who is retiring.

Trump issued no new endorsement on Wednesday but promised to do so "in the near future."

Brooks, who has made Trump's endorsement the linchpin of his campaign messaging, is locked in a three-way race to replace retiring Republican Senator Richard Shelby. His main opponents in the party's May 24 primary are Katie Britt, a former Shelby aide, and Michael Durant, a businessman and former Army helicopter pilot.

Trump has met with both Durant and Britt in recent days, according to a Trump adviser.

Republicans are favored to capture control of at least one chamber of Congress in the Nov. 8 midterm election, which would give them the power to block Biden's legislative agenda ahead of the 2024 presidential campaign.

After being an early front-runner to replace Shelby, Brooks slipped in the polls and trails his Republican rivals in fundraising. A recent poll showed him running a distant third to Durant and Britt.

Trump pulled his endorsement two days after Brooks pledged his allegiance to the former president in his running war of words against Senate Republican leader Mitch McConnell, a favorite target for Trump's invective.

A Britt campaign spokesman dismissed the Brooks pledge as an act of desperation.