All the presidents' "Gatekeepers"
They call it the toughest job in Washington - not the presidency, but those who control access to it. The White House Chief of Staff plays a critical role in the success or failure of any administration. Author Chris Whipple spoke with all 17 living people who've held the title, and joined "CBS This Morning: Saturday" to discuss his new book, "The Gatekeepers: How the White House Chiefs of Staff Define Every Presidency,"