I have been steeped in the Democratic Party all my life. My father, Jerry, was a New York City Democratic chairman and power broker, and I grew up in and around the Democratic Party. When I was a young man, former senators and Democratic presidential and vice-presidential nominees Hubert Humphrey and Estes Kefauver stayed at my apartment and we would proudly discuss the great traditions of the Democratic Party.

My father was a pallbearer at St. Patrick’s for Bobby Kennedy’s funeral. When I was young, Robert F. Kennedy and...