Thumbing his nose at both courtesy and convention, Ronald Reagan challenged incumbent Gerald Ford for the GOP presidential nomination in 1976. But why would Reagan run against a sitting president of his own party? On this episode of Whistlestop, Slate's political correspondent John Dickerson gives the background of the Gipper's ascendency to hero status in the conservative movement. For more episodes, visit the Whistlestop page.  Learn more about your ad choices. Visit megaphone.fm/adchoices