WASHINGTON — Jason Miller, a senior adviser to President Trump’s 2016 campaign, has left his position as a managing director at Teneo, a corporate advisory firm, days after attacking Representative Jerrold Nadler, the chairman of the House Judiciary Committee, in a series of tweets.

He said his departure was “by mutual consent.”

Mr. Miller used an expletive to describe Mr. Nadler and called him “fat and nasty” for his treatment of Hope Hicks, the former White House communications director, last week during an interview with the House Judiciary Committee.

During the much anticipated interview, Mr. Nadler referred to Ms. Hicks three times as “Ms. Lewandowski,” a reference to Corey Lewandowski, Mr. Trump’s former campaign manager.

Mr. Nadler said later it had been a slip of the tongue. “I just screwed it up,” he told CNN last week.