President Donald Trump’s growing feud with Steve Bannon is threatening the former White House strategist’s leadership of the conservative Breitbart News website and upending Bannon’s plans to wage “war” on party incumbents he deemed insufficiently loyal to the White House agenda.

Trump said Bannon has “lost his mind” and that he has “nothing to do with me or my presidency,” a response to Bannon’s numerous incendiary comments—including insults about the president’s family—in a new book about the first year of the Trump administration.