The freshman representative stood in front of a throng of puzzled-looking Republican congressmen. Their leader, John Boehner, had surprised the newcomer moments earlier by asking him to address a 2009 party retreat on how he had knocked off a Republican congressman in a primary. The freshman, a hard-charging Utah conservative named Jason Chaffetz, looked out at his new colleagues and said the first thing that came to his mind. “I am your worst nightmare.” He might as well have been speaking to the leader himself.