Buttigieg is well cast as a clean-cut vote seeker in New Hampshire.

Democratic presidential candidate and South Bend, Ind., Mayor Pete Buttigieg speaks in Hancock, N.H., in August. (Cheryl Senter for The Washington Post)

It’s a gorgeous day in the eye-squinting New Hampshire sunshine, a becoming natural setting for a 37-year-old candidate who seeks to embody youthful vigor and hope. Soon enough the Democratic mayor from the Midwest with the tongue-tying surname, Pete Buttigieg…