As Primaries Begin, Divided Voters Weigh What It Means to Be a Democrat

When Representative Daniel Lipinski, a conservative-leaning Democrat and scion of Chicago’s political machine, agreed to one joint appearance last month with his liberal primary challenger, the divide in the Democratic Party was evident in the audience that showed up. Mr. Lipinski’s outnumbered supporters were the diminished lunch-pail Democrats that once dominated his Southside district. Those…