"I have a duty to uphold the Constitution. And that is what I did.”

In the days after the riot at the Capitol, Mr. Rice said, he considered voting to impeach Mr. Trump, and spent that Saturday and Sunday in his home congressional district reading the dozens of stories he had asked his staff to send him about the president’s whereabouts on Jan. 6. As he learned of the president’s refusal to stop the attack, he became incensed. When it came time for his vote, he said he had “zero question in my mind” about whether Mr. Trump should be held accountable.

“I did it then,” he said. “And I will do it tomorrow. And I’ll do it the next day or the day after that. I have a duty to uphold the Constitution. And that is what I did.”…

Mr. Trump’s efforts to sway Republican primary voters and disparage Mr. Rice have left the congressman both frustrated and puzzled. He has come to view them as a political stunt.

“Bring on the circus,” he said of Mr. Trump’s involvement in the primary. “You know, some people are afraid of clowns. I’m not afraid of clowns.”