Homeland Security Secretary John Kelly will step into his new position as White House chief of staff, replacing the ousted Reince Priebus, beginning Monday, The Associated Press reports. He'll be tasked with bringing "military discipline" to a West Wing plagued by feuds, leaks, and power struggles between Trump loyalists and more conventional members of the Republican establishment. Kelly "knows how to do this: with common sense and good leadership," an unnamed friend of the retired general told The Washington Post, adding, "He won't suffer idiots and fools." Kelly has a reputation for being blunt and outspoken, as well as a history of challenging Congress.