Sen. Dave McCormick is among more than a dozen Republican senators who are defending senior White House aide Stephen Miller amid growing calls for his removal.

McCormick, a staunch ally of the president, on Sunday told The Hill that Miller has been “instrumental in delivering on the promises President Trump and I made during the campaign.”

“Because of him and other members of the President’s team, critical priorities like stopping deadly fentanyl, unleashing America’s energy, and bringing much-needed economic relief for working families are now a reality for Pennsylvania,” McCormick told the outlet.

His statement was issued along with that of 11 other Republican senators as an effort led by Sen. Lindsey Graham, R-S.C., to defend Miller, who is increasingly seen by some conservatives as a liability leading into the midterm elections.

Miller has engendered rare rebuke from some conservative corners for his public comments on immigration enforcement and speculation that Trump intends to invade and seize control of Greenland by military action.

Graham told The Hill on Sunday that Miller “is going to be proven right that we should be more aggressive” on immigration policy. He praised Miller’s and the presidents hard-line rhetoric on Greenland, arguing it has led to a strengthened Arctic defense policy.

Graham refuted that Miller’s standing in Trump’s circle was in jeopardy.

“It doesn’t matter what a senator thinks about a president’s adviser, as long as the president has confidence in that adviser. I have confidence in Stephen Miller that he’s going to help us go on offense,” Graham added. “We’re going to have a vote next week on the Senate floor on sanctuary cities and Stephen Miller helped orchestrate that with me.”

Miller is widely regarded as the architect of Trump’s overhaul of U.S. immigration policy, including its aggressive crackdown and arrests targeting immigrants. He has earned a reputation as a race-baiting provocateur, but more recently Republicans have begun to consider him a liability for the president and their party in the upcoming midterms.

“While his fellow Republicans ring alarm bells about the danger Stephen Miller’s extremism poses to our communities, Dave McCormick is putting his loyalty to Trump’s dangerous agenda ahead of what’s best for Pennsylvanians,” said Jack Doyle, a Pennsylvania Democratic Party spokesperson.

“Whether he’s defending Stephen Miller or endorsing Stacy Garrity, who is running to serve as a rubber stamp for Trump here in the Commonwealth, Dave McCormick continues to embrace extremism at the expense of the people he is supposed to be fighting for.”

Sen. Thom Tillis, R-N.C., assailed Miller in comments made to The Hill on Sunday.

“I think the truth be told he would not win a majority of a popularity contest in our conference,” he said. “Number one, he has a condescending demeanor to begin with. He doesn’t take advice. He sort of dictates. He provides doctrine. And you know these are U.S. senators with an election certificate. He should show them some respect,” Tillis said of Miller.

The North Carolina Republican has rebutted comments made by Miller on potential military action to take over Greenland.

Last month, he called comments that Miller had made “insane” and “amateur hour.” Tillis famously said he was “sick of stupid” in reference to Miller.

McCormick recently marked his first year in office.