The Justice Department’s decision last week to drop its criminal investigation of Federal Reserve Board Chair Jerome Powell demonstrated the leverage a single Republican lawmaker can wield over the Trump administration.
As ostensibly the deciding vote in the Senate Banking, Housing, and Urban Affairs Committee, Sen. Thom Tillis was able to strong-arm the DOJ by threatening to block Trump nominee Kevin Warsh’s confirmation as Powell’s successor unless the much-criticized probe was scrapped. It worked. Now, other GOP lawmakers might take notice.
Trump has long used his MAGA base to keep Capitol Hill Republicans in line. The lack of competitive House seats—The Cook Political Report rates only 32 of the 435 as “toss-up” or “lean” this year—means the vast majority are decided at the primary level, where a Trump endorsement in a red district often decides the outcome.
Trump remains hugely popular among Republicans. But that will be less of a weapon as the primary season starts to ebb and GOP lawmakers start pivoting toward the middle in some areas to curry favor with independents who have largely soured on the president. Another crop of members have already announced their intentions to leave Capitol Hill at the end of their terms, giving them more freedom to break from the White House.
That includes Tillis, who decided not to run after Trump berated him last year for voting against the president’s signature tax and spending bill, citing concerns over Medicaid cuts. Not having to face reelection, the North Carolina Republican has been free to vote his conscience—including on his decision to stall Warsh, a nominee he praised for having “impeccable credentials,” because of the Powell probe. The slim GOP majorities in both chambers mean that such renegades have more power than usual—if they decide to use it.
So which other Republicans are worth keeping an eye on?
Sen. Bill Cassidy of Louisiana: The chairman of the Health, Education, Labor, and Pensions Committee held his nose last year when he voted to confirm Robert F. Kennedy Jr. as Health and Human Services secretary. The two have clashed over vaccines, but Cassidy has (mostly) bitten his tongue, hoping to get Trump’s endorsement for his reelection this year. Trump instead blessed challenger Julia Letlow in the upcoming GOP primary, payback for Cassidy’s vote to convict Trump on impeachment charges involving the Jan. 6 insurrection.
If Cassidy loses—or even if he wins—the former liver doctor would face fewer political consequences if he decides to use his powerful perch to push back against Kennedy's agenda, particularly on immunization schedules. Cassidy’s skepticism of surgeon-general nominee Casey Means over the issue of vaccinations no doubt contributed to the president’s decision to pull the nomination Thursday.
Rep. Don Bacon of Nebraska: The genial ex-Air Force general, who is not seeking reelection to his blue-leaning district, supports much of Trump’s military agenda regarding the Iran campaign, an increased military budget, and modernization of the nuclear triad. But he’s also unhappy with the Pentagon’s dismissal of well-respected service chiefs, telling Defense Secretary Pete Hegseth on Wednesday that while he had the authority to make those moves, “it doesn’t make it right or wise.” Bacon, who holds the gavel on the Armed Services Cyber, Information Technologies, and Innovation Subcommittee, also chairs the House Baltic Caucus and is a strong supporter of Ukraine.
While Bacon supports the war against Iran, he wants Congress to be more involved. Under the War Powers Act of 1973, presidents must seek congressional approval to continue military force. Speaker Mike Johnson has said the issue is moot because the U.S. is “not at war” with Iran, but Bacon and other Republicans could push the issue and force a vote.
Sen. John Cornyn of Texas: Long an establishment voice on Capitol Hill, Cornyn began veering more to the right around the time his reelection cycle came into view. He faces a May 26 Republican primary runoff against Texas Attorney General Ken Paxton, whose hard-right record has turned the race into a toss-up. Trump has not endorsed either man, which could give Cornyn less incentive to push Trump’s agenda if he loses the nomination.
The Texas senator has been an influential GOP voice calling for a repeal of the filibuster he used to champion in order to pass the SAVE America Act, which would make casting a ballot more challenging nationwide. A lame-duck Cornyn might be less willing to ditch the filibuster as Trump has been pressuring the Senate to do.
Rep. Dan Newhouse of Washington: Newhouse already has a history with Trump, having voted in 2021 to impeach the president over his role in the Jan. 6 insurrection. In February, he was one of six Republicans to cross the aisle as he voted to end Trump’s tariffs on neighboring Canada, saying they had “harmed Washingtonians.”
Trade wars will continue to dominate Trump’s economic and foreign policy agendas. Newhouse said Congress “must play a strong role” in any renegotiation of the United States-Mexico-Canada trade agreement, which is up for review in July. The president, who once praised the pact that originated in his first term, has since dismissed it as “irrelevant.” Newhouse, who is not running for reelection, could play an important role in any House vote on proposed changes.
Rep. Chip Roy of Texas: The Freedom Caucus member is giving up his seat to run for attorney general in the Lone Star State. Though he and Trump have clashed on spending priorities and fiscal responsibility, the congressman has been careful in his criticism of the president, as he needs MAGA voters in his contested GOP runoff election on May 26.
If Roy loses the runoff, he’ll be less bound to sign off on the administration’s budget bills or any initiatives that add money to the nation’s growing national debt (nearly $39.2 trillion and climbing).
Rep. Nancy Mace of South Carolina: Like Roy, Mace is trying to jump from Congress to statewide office—in her case, governor. After Jan. 6, Mace said she held the president “accountable” for the actions of the mob and that it was time to “rebuild the Republican Party” with a new voice. She’s since made up with the president and has become a loyal soldier for him, although he did not endorse her for governor in a state he won by nearly 18 points in 2024.
Despite her support for Trump, she’s not budging on Jeffrey Epstein. Mace has not accused Trump of wrongdoing in his years-long relationship with the financier-turned-sex offender, but she has ignored the president’s call to close the books on the scandal that has ensnared a number of high-profile figures. It was Mace who led House Oversight Committee efforts to subpoena Trump’s former attorney general, Pam Bondi, to testify on May 29. If she loses her gubernatorial primary in June, Trump may have a harder time sweeping Epstein under the rug.
