WASHINGTON — Stephen K. Bannon stepped down on Tuesday from his post as executive chairman of Breitbart News, ostracized for now from conservative circles and the Republican Party he brazenly predicted he would remake.
Mr. Bannon’s departure, which was initiated by an estranged financial patron and Breitbart investor, Rebekah Mercer, came as Mr. Bannon remained unable to quell the furor over remarks attributed to him in a new book in which he questions President Trump’s mental fitness and disparages his son Donald Trump Jr.
Mr. Bannon and Breitbart will work together on a smooth transition, said a statement from the company’s chief executive, Larry Solov. Separately, SiriusXM, which broadcasts a radio show on which Mr. Bannon was a host, said it was also cutting ties with him.
Mr. Bannon’s exit from Breitbart, a platform for hard-edge nationalist ideas, is the latest ignominious turn in a career that was once one of the most prominent and improbable in modern American politics.
Though he was virtually unknown outside his work at Breitbart, Mr. Bannon was named chief executive of the Trump campaign two and a half months before Election Day. And he helped instill the discipline and focus that allowed Mr. Trump to narrowly prevail in the three Midwestern states that gave him victory in the Electoral College.
