For the past 50 years, the race to become the Democratic Party’s presidential nominee has been shaped by the where the contest begins: Iowa. But that process could soon be overhauled. In a coming meeting of the Democratic National Committee, South Carolina — a state that is more representative of the party and, possibly, of the country — could take over the key role of going first. Guest: Adam Nagourney, a West Coast cultural affairs correspondent for The New York Times.