PHILADELPHIA—Minnesota Gov. Tim Walz debuted as Vice President Kamala Harris’s running mate at a campaign rally here on Tuesday evening, just hours after being announced as the nominee. 
Walz, a former high school football coach and 24-year veteran of the Army National Guard, lived up to his reputation at the event as a plainspoken Midwesterner. He salted his remarks with homespun expressions and presented his left-of-center policy positions with a personal touch. 
The rally kicks off a weeklong tour of battleground states in which the duo will visit Wisconsin, Michigan, North Carolina, Georgia, Arizona, and Nevada. 
An overflow crowd of more than 10,000 people braved 90-degree temperatures and occasional rain showers while waiting in a line stretching some five blocks to enter the Liacouras Center at Temple University on the city’s north side. …