Republican members of the Senate who are up for re-election in 2026 are already facing primary challenge threats as they weigh whether to back some of President-elect Trump’s cabinet picks. Questions around the viability of some of Trump’s national security nominees has Trump’s more populist supporters especially incensed that senators aren’t backing nominees who intend to crack skulls in the federal bureaucracy. 

The president-elect has already lost one cabinet nominee this year, with Congressman Matt Gaetz pulling out of consideration for the attorney general position after just eight days because it became clear that Republican senators had little appetite to go to the mat for him. Trump’s pick to lead the Drug Enforcement Agency also pulled out after MAGA objected to how  he enforced Covid restrictions on the faith community in his Florida county.

Following the 2016 election, Trump had just one nominee fail, though this time he is in danger of losing more. With Mr. Gaetz out of the way, the Senate’s scrutiny and much of the press attention has turned to other controversial cabinet nominees, though the man in the hot seat for the time being is Pete Hegseth.

Mr. Hegseth has been nominated to lead the defense department but is now facing accusations of sexual misconduct and alcohol abuse. The Hill reported earlier this week that Trump’s choice for Director of National Intelligence, Tulsi Gabbard, may have the most difficult path to confirmation due to senators’ concerns about her foreign contacts. 

Regarding Mr. Hegseth, multiple senators — some of whom are deeply conservative in ruby red states — have yet to commit to supporting Mr. Hegseth’s nomination. An Army veteran who has tried to reform the military justice system’s response to sexual assault claims, Senator Ernst, is running for re-election in just two years, yet she has hinted she may not support Mr. Hegseth’s nomination.

On Thursday morning, she was pressed by Fox News host Bill Hemmer, who told Ms. Ernst that it “doesn’t sound like” she’s going to be supporting Mr. Hegseth on the Senate floor or in the Armed Services Committee vote. Ms. Ernst responded: “I think you’re right.”

That admission followed a lengthy meeting with Mr. Hegseth on Wednesday. After meeting with the nominee, Ms. Ernst said she had “a frank and thorough” conversation with Mr. Hegseth, and that they shared a love of country, but declined to tell reporters anything beyond that. 

The comments on all of Ms. Ernst’s social media posts were quickly flooded with threats of a primary challenger in Iowa, though no one floated a specific name. All four of Iowa’s Republican members of Congress are close with the senator, and would not likely run against her. 

Another deeply conservative senator who is not committed to Mr. Hegseth is Senator Capito, who has represented West Virginia in the Senate for the last decade and who plans on running for re-election in 2026. 

On Wednesday, she said she would let the “process” play out, but confirmed that she had not yet made up her mind on Mr. Hegseth’s nomination. 

Ms. Capito is already facing a primary challenger, well before she announced she may not back Messrs. Gaetz and Hegseth. A former state delegate, Derrick Evans, is running against her. His greatest claim to fame is participating in the January 6 riot at the Capitol, livestreaming on Facebook while shouting “Derrick Evans is in the Capitol!” He was arrested three days later, was forced to resign from West Virginia’s House of Delegates and was sentenced to three months in prison. In May, he lost a primary challenge for a U.S. House seat.

One of the few Republican senators up for re-election in 2026 who is not in a deep-red state, Senator Tillis, a relatively moderate conservative who narrowly won re-election in 2020 after his opponent was exposed for an extramarital affair, is starting to walk hand-in-glove with Trump on the nomination fights for fear of a primary challenge. 

He refused to commit to supporting Mr. Gaetz’s nomination, but  now says he plans to back “all” of the president-elect’s cabinet picks. That promise came just hours after North Carolina’s controversial lieutenant governor, Mark Robinson — who lost this year’s gubernatorial election in a blowout — hinted that he may run against Mr. Tillis in the Republican primary in two years. 

“Should Thom Tillis be the 2026 nominee for US Senate in North Carolina?” Mr. Robinson asked in a poll on X, to which just one-in-five followers responded “yes.”

“Thom is toast,” the lieutenant governor wrote in a follow-up message, which included a gravestone emoji. 

One of the Democrats’ top targets for 2026 beyond Mr. Tillis is a Republican in a blue state whose approval rating in Maine is just 43 percent according to the most recent Morning Consult survey from earlier this year, Senator Collins. The activist Riley Gaines, who campaigns against biological men being allowed to compete in women’s sports, says Mainers should “remember” Ms. Collins’ lack of support for Trump’s nominees when she is up for re-election in two years. 

Other Republicans have cautioned against a primary challenge against Ms. Collins, however, just given her ability to defy political gravity in a state that hasn’t been won by a Republican presidential candidate since President George H.W. Bush in 1988. Ms. Collins, along with Senator Murkowski, are expected to vote “no” on Trump’s more controversial cabinet nominees.

“This is not the time to look at alternatives. This is the time to attack. We need @PeteHegseth in any Republican center who gets in the way should get our undivided attention at primary time,” conservative writer Kurt Schlichter wrote on X. “Except Susan Collins. That’s just counterproductive.”