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Republican senators’ battle against MAGA-inspired primary opponents hoping to win Donald Trump’s favor officially started days ago in Louisiana, where the first Facebook ads began running for a campaign that’s two years away.
One of the ads urged Louisiana Sen. Bill Cassidy to “support Pete Hegseth” for defense secretary. Another told Republican voters how to encourage Cassidy “to vote for all of Trump’s nominees” — follow state treasurer John Fleming, Cassidy’s brand-new GOP primary challenger.
“I’m openly and publicly supporting all of [Trump’s] nominees,” Fleming told Semafor. “It doesn’t mean that I necessarily agree with everything they’ve said in the past. But I trust President Trump.”
As they weigh the president-elect’s Cabinet picks, incumbent GOP senators are facing serious pressure to vote his way if they want to avoid tough and costly primary challenges. Trump confirmed as much on Monday, telling reporters that if Republicans are “unreasonable, if they’re opposing somebody for political reasons or stupid reasons,” then those senators would be primaried.
Trump won’t take office for more than a month, but his comments followed already-intense conservative media pressure and organized calls to Senate offices pushing Republicans to back Trump’s nominees. The effect of the MAGA-driven campaign is already palpable, but some of the targeted Republicans are taking it in stride.
Sen. Thom Tillis, R-N.C., told Semafor that he is guaranteed to draw a primary challenge in 2026 and that Trump has a “valid point” in asking GOP senators to explain their opposition to Cabinet nominees. Tillis has indicated he’ll support any Trump pick who gets out of Senate committees and on to a full vote.
“You just can’t be ‘no’ because you want to be ‘no.’ You have to be ‘no’ because these questions do not not satisfy in my own mind, that this is the right pick,” Tillis said.
Still, he added that senators deserve space to make decisions: “The last time I thumbed through the Constitution, I heard it say ‘advise and consent,’ not ‘bludgeon and confirm.’”
Cassidy has not come out against any of Trump’s nominees thus far and expressed confidence they can work together, though Fleming said Louisiana’s GOP voters remain “very, very angry” with the senator’s vote to convict the president-elect in his 2021 impeachment trial. Fleming, who lost a Senate race in 2016, will face Cassidy in a more traditional Republican-on-Republican primary after the state got rid of its top-two “jungle” system, which more candidates could enter.
His challenge to Cassidy is a signal of the internal friction that Republican senators might face elsewhere. As former Trump adviser Steve Bannon put it recently: “If they don’t toe the line, they get a MAGA primary — and they will get a MAGA defeat.”
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No GOP senator has lost a primary since 2017, and only Cassidy already faces a well-known challenger so far. Yet Republicans are girding for more as they defend more than 20 seats across the country in 2026.
They’ll also have to rebuild some political muscle memory. They have a new leader, John Thune of South Dakota, and will have a new chief at their super PAC as Steven Law steps down from the Senate Leadership Fund. Typically, GOP leaders and SLF protect incumbent senators; Thune indicated he will keep that policy, telling Semafor on Tuesday that “we back incumbents.”
“We’ve got to figure out how to work together. Part of this is politics in the modern era. Primaries are kind of a fact of life for a lot of us,” Thune said.
The Senate primary threats follow Trump’s successful challenges to most of his biggest critics in the House after his second impeachment. The tension is particularly acute on behalf of Hegseth, with Bannon and his allies bombarding GOP offices.
“We gave senators an attitude adjustment,” said Mike Davis, a pro-Trump legal activist whose Article III Project has driven thousands of calls and emails in support of Hegseth’s nomination.
Hegseth still is not a lock for Senate confirmation, but his prospects are looking better after that effort. It could be the start of a trend.
”I don’t think they’re gonna have a problem getting nominees across the finish line, at this stage of the game,” said Sen. Mike Rounds, R-S.D., another incumbent up for reelection in 2026.
Sen. Susan Collins, R-Maine, who’s also up in two years, said Trump’s comments on Monday were not “helpful” and that she will do her due diligence on his nominees no matter what: “I may well have a primary challenge, but that does not enter into my calculation on how I’m going to vote on nominees.”
She generally hasn’t faced primary challenges in the past, as the only GOP senator representing a reliably blue state, but Collins said she takes the prospect seriously.
“Primaries are tricky. Turnout can be small, you know, so I never take anything for granted,” she told Semafor.
Trump has helped purge his critics from the House and played kingmaker in some Senate primaries. That’s encouraged conservative activists to keep their sights trained on incumbent senators despite recent struggles against them.
Joshua Smith, a libertarian-turned-Republican who’s mounting an uphill challenge to Sen. Joni Ernst, R-Iowa, said that he got in the race because of her support for foreign military aid to Ukraine and Israel.
“Iowa went to bat for Trump, big time,” Smith told Semafor. He said he has messaged Donald Trump, Jr. about the race but has not heard back yet.
Ernst’s failure to embrace Hegseth immediately, he added, “was really stupid for her political career.”
Back in North Carolina, outgoing Lt. Gov. Mark Robinson polled his X followers on whether Tillis should be the party’s 2026 Senate nominee. Robinson’s conclusion, even after losing the gubernatorial race by 15 points last month? “Thom is toast.”
In an interview, Tillis quickly dismissed Robinson’s scandal-tarred record as a deal-breaker in a primary: “I don’t think I have to prepare for Mark Robinson. Mark Robinson’s record is enough for me. It’s content-rich.”
He also downplayed the idea that Lara Trump would run against him in North Carolina because of her prospects of securing a Senate appointment in Florida.
The View From Democrats
The biggest risk for Republicans is that MAGA-driven primaries will hurt their chances to hold onto Senate control, an outcome that Democrats certainly don’t mind.
“Most of these nominees are bad news for anyone who wants to run for statewide office,” said North Carolina Rep. Wiley Nickel, a Democrat who’s looking at a 2026 run for Tillis’ seat. “If you support any of these far-right extremist candidates, you should be held to account by the voters.”
Rep. Troy Carter, D-La., said Cassidy’s impeachment vote was “courageous,” and one he knew would complicate his re-election: “The president-elect has demonstrated that he goes after his enemies.”
David and Burgess’ View
The last GOP senator to lose a primary was Alabama’s Luther Strange, who fell to Roy Moore even though Trump had endorsed Strange. But the world, and the GOP, have changed since then: Loyalty to the incoming president has overwhelmed nearly any other potential litmus test for Republican candidates.
So it would be a mistake to look at this cycle’s crop of aspiring primary challengers as a MAGA version of the Tea Party. We’re more likely to see most incumbent Republican senators edge closer to Trump’s camp — a subtle way to address the opposition.