Representative Steve King of Iowa, who was stripped of his House committee seats on Monday night after making remarks defending white supremacy, has a long history of racist comments and insults about immigrants.

Republicans rarely rebuked him until recently, with some suggesting that Mr. King’s language and views were new to them.

“This just popped up on Friday,” Representative Steve Scalise, the second-ranking House Republican, said on Sunday, when asked if the party would penalize Mr. King for saying, in an interview with The Times, “White nationalist, white supremacist, Western civilization — how did that language become offensive?”

National Republicans courted his political support in Iowa: He was a national co-chairman of Ted Cruz’s 2016 presidential effort and of Gov. Kim Reynolds’ 2018 election. House leadership appointed him chairman of the subcommittee on the Constitution and civil justice. And President Trump boasted in the Oval Office that he raised more money for Mr. King than for anyone else.