The divides between the Democratic old guard and a new class of progressive challenger were on sharp display on Tuesday night as a congressional candidate in New York’s 13th District apologized for past disparaging remarks about Kamala Harris.

The Democratic Socialist is trying to win Adriano Espaillat’s House seat. Her old social-media posts may be the only thing standing in her way.

The divides between the Democratic old guard and a new class of progressive challenger were on sharp display on Tuesday night as a congressional candidate in New York’s 13th…