The rally’s purpose was to introduce Mr Walz, and to begin selling the rich Americana in his biography. Ms Harris seemed particularly impressed by Mr Walz’s long-ago side job as a “Friday Night Lights” American-football coach at the high school where he also taught social studies. She repeatedly referred to her running-mate as “Coach Walz” and conveyed an impression that the duties of a vice-president, admittedly vague, might somehow include winning sports championships. Overall, Ms Harris made clear why she had selected Mr Walz from a shortlist of qualified finalists. She positioned his life story—humble origins in small-town Nebraska, military service, teaching, responsible gun ownership, and not a whiff of law school or Wall Street fortune-hunting on his résumé—as a testament to her campaign’s Biden-esque focus on the middle class.