Rep. Steve Stivers, chairman of the House GOP campaign arm, excoriated Iowa Republican Rep. Steve King on Tuesday for espousing white supremacist viewpoints online and in public remarks.

"Congressman Steve King's recent comments, actions, and retweets are completely inappropriate. We must stand up against white supremacy and hate in all forms, and I strongly condemn this behavior," Stivers, of Ohio, said in a tweet.

King is an anti-immigration hardliner who has in several instances railed against diversity in America, saying it is "not a strength," and asking, "What does it bring that we don't have that is worth the price?"

Republicans on Capitol Hill have faced criticism for leaving King's behavior unchecked. Stivers, who chairs the National Republican Congressional Committee, is the most prominent member of the party to denounce King's behavior.

In a statement released on Tuesday, King said he valued the country's diversity and "legal immigrants." He then criticized the news media and suggested "establishment" anti-Trump Republicans are "complicit" in helping Democrats who want to remove Trump from office.

Recently, King praised Austria's Freedom Party, which was founded by a former Nazi SS officer, for its anti-immigration platform. "If they were in America pushing the platform that they push, they would be Republicans," King told the Washington Post.

In a tweet earlier this month, the Iowa Republican endorsed a candidate running for mayor in Toronto who has espoused white supremacist views and questioned if Canada is facing a "white genocide."

King also prompted backlash last year after he said U.S. culture cannot be restored "with somebody else's babies" and advocated for "an America that's just so homogeneous that we look a lot the same." And King has called Western civilization a "superior culture" and refused to delete a retweet of a far-right British immigration activist who has questioned the Holocaust and had blamed slavery on Jewish people. He displays a confederate flag on his desk in Washington, D.C.

King, however, has remained in good standing with President Donald Trump. Trump headlined a rally in Council Bluffs, Iowa, earlier this month to boost Republicans in the state, including King. He said King "may be the world's most conservative human being” and the president said he supported King "long before I became a politician."

As a result of his remarks, the dairy company Land O' Lakes Land said on Tuesday it would no longer make political donations King's re-election campaign. The tech giant Intel said it would also stop supporting the lawmaker.

The Cook Political Report recently downgraded King's chances, moving the rating on his reelection bid for Iowa's 4th district from "likely" Republican to "leaning." He is running against Democrat J.D. Scholten.

King has thus far refused to apologize for his comments. In a tweet earlier this month, he said, "It’s the message, not the messenger," when rebuffing criticism of him supporting white supremacist positions.

"I will retweet the devil if the devil tweets, 'I Love Jesus,'" he wrote.