Will Kamala Harris regret picking Tim Walz over Josh Shapiro?

Vice President Kamala Harris chose Minnesota Gov. Tim Walz as her running mate Tuesday.

Walz’s selection came as something of a surprise. For much of last week, betting markets had given Pennsylvania Gov. Josh Shapiro a more than 60 percent chance of joining the Democratic ticket. In opting for Walz instead, Harris defied the conventional wisdom among Democratic consultants, who had broadly favored Shapiro. And on Tuesday morning, some close to the Trump campaign told CNN that they were “breathing a sigh of relief” that the Democratic nominee had not tapped the popular Pennsylvania governor.

The wisdom...