After the assassination attempt on former President Donald J. Trump in Butler, Pa., Congress held hearings on the failures of the Secret Service, and its director, Kimberly Cheatle, stepped down. Weeks later, another man attempted to shoot the former president, increasing concerns that something had gone very wrong at the Secret Service. Eric Lipton, an investigative reporter for The New York Times, explains why the agency’s failures are indicative of much more troubling issues. Guest: Eric Lipton, an investigative reporter for The New York Times.