Sen. Thom Tillis, R-N.C., on Sunday blasted those who have promised to fund primary challenges against Republican senators who oppose President-elect Donald Trump’s Cabinet picks, calling them “political opportunists.”

“We’re not even in the new administration,” Tillis said in an interview on “Fox News Sunday.” “We haven’t even seen the background checks, which I know the administration is sending our way.

“So there’s a lot of information that needs to be gathered, and these folks who are making primary challenges, running ads, they seem more like political opportunists than me than thoughtful members of the Republican Party,” he added.

Tillis said he doesn’t believe the threats are coming from Trump. “A lot of these are third parties that are making money from the fundraising campaigns to put some ads in there, but double-digit percentages are going into their pockets,” he said. “Here’s what I would tell them: If they really support President Trump’s nominees, they should stand down and let the nominees win on their own merits, and I think most of them will.”

He added that he doesn’t believe the pressure campaigns are in “good service” of Trump.

Tech mogul Elon Musk, who spent over $250 million during the election to boost Trump, has suggested he would support intraparty challenges to those in the GOP who don’t back Trump’s nominees.

Several of Trump’s picks have drawn scrutiny from members of the Senate, which must vote to confirm their appointments, including former Democratic Rep. Tulsi Gabbard, whom Trump picked to be director of national intelligence, and Robert F. Kennedy Jr., his pick to lead the Department of Health and Human Services.

Last month, Musk responded to reports that he was threatening to fund primary challenges to House Republicans who didn’t “fall in line with Trump’s agenda.”A user on X, which Musk owns, responded, “And that is how you drain the swamp.” Musk responded to the user: “How else? There is no other way.”

And Musk and Turning Point USA founder Charlie Kirk threatened this month to support primary challengers to Sen. Mike Rounds, R-S.D., who questioned Trump’s nomination of Kash Patel to lead the FBI.

“Senator Rounds, you are up for reelection in 2026. If you vote against any of Trump’s nominees a primary challenge wouldn’t be hard,” Kirk wrote on X.

Musk replied, “Those who oppose reform will lose their primary/election. Period.”

Kirk also blasted Sen. Joni Ernst, R-Iowa, who previously indicated she had reservations about former Fox News host Pete Hegseth’s selection to lead the Defense Department.

Grassroots activists in Iowa have publicly decried Ernst’s hesitation about Hegseth, and Kirk this month called out Ernst and Sen. Lindsey Graham, R-S.C., writing on X: “Being told Joni Ernst and Lindsay Graham are trying to end Pete Hegseth … Pete Hegseth is the redline. If you vote against him, primaries will ensue.”

The conservative group Heritage Action also announced last week that it would launch a $150,000 digital campaign targeting Senate Republicans in Alaska, Maine, Louisiana, Iowa, North Carolina, Kentucky, Indiana, Utah and South Dakota who are on the fence about supporting Trump’s nominees.

“Americans gave President Trump a mandate on November 5 to implement and pass his top priorities as quickly as possible. The Senate must now do its part to have Cabinet appointees confirmed and ready to go to ensure this conservative mandate can be carried out effectively,” Heritage Executive Vice President Ryan Walker said in a statement announcing the campaign.

The pressure campaign and primary threats aren’t the first time Tillis has faced scrutiny for deviating from Trump. Last year, the North Carolina Republican Party censured Tillis at its annual convention, citing Tillis’ “blatant violations of our party platform.”

On NBC News’ “Meet the Press” on Sunday, Graham dismissed the pressure campaign against GOP senators, telling moderator Kristen Welker: “At the end of the day, yeah, people will push you to do things up here. It’s up to you to resist.”

He added that he’s open to meeting with Trump’s selections and fairly weighing each of them on their merits, saying, “But I’m going to do what I think is best for the country, and that’s have a process that works.”

Tillis on Sunday downplayed the hesitation of some GOP senators who haven’t publicly supported each of Trump’s picks yet, including Patel and Hegseth.

“Kash Patel, who I’m working with, because he’s on my committee of jurisdiction, is going to enjoy solid Republican support on the Senate floor and coming out of the committee,” Tillis said.

Tillis said Hegseth “is going to have to go to the committee and answer some questions about organizational experience, some of his past marriages, those sorts of things. All of that’s fair game when you’re running for a Cabinet or sub-Cabinet position.”

Spokespeople for the Trump transition team, Turning Point Action and Heritage Action didn’t immediately respond to requests for comment about Tillis’ remarks.