Washington (CNN) The head of House Republicans' campaign arm sharply criticized Iowa GOP Rep. Steve King's white nationalist rhetoric on Tuesday, just a week before King faces an unexpectedly competitive election.

Rep. Steve Stivers of Ohio, the chairman of the National Republican Congressional Committee, tweeted: "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."

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. — Steve Stivers (@RepSteveStivers) October 30, 2018

A National Republican Congressional Committee aide said it was the growing volume of King's remarks, rather than a specific incident, that led to the unusual rebuke.

Responding to Stivers' tweet with one of his own Tuesday afternoon, King didn't directly address the chairman or the controversies over his own statements and actions. Instead, King said: "Americans, all created equal by God, with all our races, ethnicities, and national origins-legal immigrants & natural born citizens, together make up this Shining City on the Hill. These attacks are orchestrated by nasty, desperate, and dishonest fake news. Their ultimate goal is to flip the House and impeach Donald Trump. Establishment Never Trumpers are complicit."

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