Aside from the president himself, Chief of Staff Reince Priebus is arguably the most powerful person in the White House. Chris Whipple joins us to talk about the many roles these presidential assistants play – from pushing out their bosses’ agendas to negotiating with Congress. His new book is called “The Gatekeepers: How the White House Chiefs of Staff Define Every Presidency” (Crown). He speaks tonight at Highland Park United Methodist Church as part of Authors Live!