GOP Rep. Ken Buck plans to challenge his party's direction under Trump as he leaves the House

WASHINGTON (AP) — Rep. Ken Buck has had enough.

When the Colorado Republican announced this past week that he would not seek reelection, he began with the type of criticism of Democratic policies that is standard fare for a hard-line conservative. But then Buck turned his ire to fellow Republicans, spending most of the three-minute announcement video accusing them of being “obsessively fixated on retribution and vengeance for contrived injustices of the past.”

Buck's scorched-earth approach caught few on Capitol Hill by surprise.

With a deadpan demeanor, an independent streak and a background as a federal prosecutor, Buck has gained national prominence as a House Republican fed up with Donald Trump’s lies about the 2020 presidential election he lost to Democrat Joe Biden and the Trump allies in Congress who amplify them. It's a stand few others in the GOP are taking and is a remarkable turn that shows just how deeply Trump's once-fringe lies about that race have settled into the Republican mainstream.

Buck regularly appears on networks such as CNN and, with no plans to leave Congress before the end of his term, he probably will be a prominent foil to Republicans during his final months in office. His political heresy extends to the impeachment inquiry into Biden, which Buck has dismissed as baseless.

“Our nation is on a collision course with reality, and a steadfast commitment to truth — even uncomfortable truths — is the only way forward,” Buck said in the video.

Yet under political pressure in Colorado, Buck decided there was no way forward for him in Congress.

Trump celebrated Buck's impending departure, saying on social media that the congressman “knew long ago he could never win against MAGA, so now he is, like some past and present, auditioning” for a network television job. “MAGA” is short for the 2016 Trump campaign slogan, “Make America Great Again.”

Buck is hardly the first GOP lawmaker to step away from Capitol Hill in frustration in recent years. But unlike other outspoken House Republicans who grew alienated from their colleagues before leaving office, such as former Reps. Liz Cheney of Wyoming or Adam Kinzinger of Illinois, Buck hails from the far-right House Freedom Caucus, putting him at the center of the conservative movement.

Nearly every week, Buck leaves the Capitol complex to attend caucus meetings, where lawmakers strategize about how to disrupt business as usual in Washington. He has proposed drastic budget reductions, strict sanctions against TikTok and cuts for educational material that teaches slavery was central to the nation's founding.

Buck was also among the eight Republicans who voted to remove Rep. Kevin McCarthy, R-Calif. as speaker and accused him of failing to follow through on his promise to slash spending.

“The critical issue for me is to bend the spending curve and you do that with institutional changes,” Buck told The Associated Press in September. “Nobody has been willing to change this place.”

While Buck in his five House terms has aggressively pushed policy to the right, he has simultaneously resisted what he calls “a populist flavor in the party” that has ascended with Trump.

“Ken is a constitutionalist who tries to make good decisions based on principle,” said Texas Rep. Chip Roy, a fellow caucus member. "I think he’s an important voice, and I’ll certainly miss him.”

Buck has publicly feuded with Rep. Marjorie Taylor Greene, R-Ga., a high-profile Trump ally who calls Buck a “CNN wannabe.” Buck has criticized how Greene and other Republicans have become public advocates for people charged in the Capitol riot on Jan. 6, 2021.

“When I was teaching law school, I learned and taught certain constitutional principles,” Buck told a Denver radio show, referencing his time at the University of Denver. “When Marjorie Taylor Greene was teaching CrossFit, she learned a whole different set of values, evidently, because my idea of what this country should be like is based on the Constitution.” Greene was once a co-owner of CrossFit affiliate gym in Georgia.

Buck's experience in constitutional law predates his time teaching law school. After completing a bachelor’s degree at Princeton University and a law degree at the University of Wyoming, Buck worked for then-Wyoming Rep. Dick Cheney, who was the top Republican on the committee investigating the Reagan administration for the Iran-Contra affair. Cheney, who is Liz Cheney's father, eventually issued a minority report that argued that President Ronald Reagan had wide latitude to conduct foreign policy and described the president's actions as “mistakes in judgment, and nothing more.”

Buck called Iran-Contra a “constitutional crisis” that impressed upon him the importance of Congress not overstepping its powers. He also said a different approach to politics ruled Washington in those days: Democratic and Republican lawmakers were genuinely friends and built trust that led to bipartisan achievements.

Buck later returned to the West and a law career that included directing the criminal division of the U.S. attorney's office in Colorado. He departed the office after receiving a reprimand for remarks he made about a case to a defense attorney for gun dealers that undermined the prosecution. Buck was later elected as a district attorney in northeast Colorado.

Buck reentered national politics as the tea party gained prominence, and he ran against Democratic Sen. Michael Bennet in 2010. Buck lost, and Colorado, then a battleground state, has become increasingly dominated by Democrats.

In 2014, Buck made a comeback, winning a House district that spans the entire eastern third of the state, from ranch land to Denver suburbs.

During his five terms in Congress, Buck for a time held a spot on the powerful House Rules Committee, where he sat next to Liz Cheney. He also was the top Republican on the House Judiciary's antitrust subcommittee. He gained a reputation as a strict conservative who would listen to Democrats and work with them on occasion.

“I’ve always found him to be incredibly straightforward, intellectually curious, willing to disagree without being disagreeable,” said Rep. Joe Neguse, a Colorado Democrat who represents a district adjacent to Buck's.

Buck formed an unlikely alliance with former Rep. David Cicilline when the Rhode Island Democrat was chairman of the antitrust panel. They managed to advance a series of bills that sought to diminish the power that tech companies such as Amazon, Apple, Meta and Google hold in the online market. Some bills were signed into law by Biden.

Cicilline said Buck defied the will of both Ohio Rep. Jim Jordan, who was the Judiciary Committee's top Republican and is now the chairman, and McCarthy, who was the House Republican leader before becoming speaker, as Buck worked on the investigations into the tech companies.

“He has demonstrated that he does what he thinks is right, even if it means standing up to his own party leadership,” said Cicilline, who left office in May to head a nonprofit.

In recent weeks, Buck was at the center of moves against both McCarthy and Jordan. He provided a crucial vote to oust McCarthy. Then when hard-line conservatives made Jordan the Republican nominee for speaker, Buck voted against him. Alone among Republicans, Buck said he was opposing Jordan because he had not clearly stated that Biden won the 2020 election.

Buck said opposing Jordan unleashed a wave of vitriol from Republican activists and led to him being evicted from a district office in Colorado.

This past week, Trump called Buck a “weak and ineffective Super RINO,” or Republicans In Name Only. The next day, Buck testified about a legal effort in Colorado to ban Trump from the ballot under the Constitution’s “insurrection clause." True to form, Buck's stance defied easy categorization. He testified against banning Trump from the election.

Buck said the events of recent weeks showed him the House no longer allowed for reasonable disagreement.

“This is a real honor to serve here," he said, "But it’s also a pain in the rear end."