CEDAR RAPIDS, Iowa – Mayor Pete Buttigieg, the Democrats’ wunderkind from South Bend, Indiana, has made only a modest mark in national polls, yet he’s a boffo attraction in Iowa as well as in California, where he’s the favorite among Hollywood’s glitterati.

Watching him in action at the annual Corn Feed, as they’ve named a day of political speeches here in Cedar Rapids, it’s easy to understand Buttigieg’s appeal. He’s closer to the center tha...