In the dining room of the Naval Observatory on Sunday, Tim Walz sat across from his soon-to-be running mate for the biggest interview of his life. His message to Kamala Harris and her vetting team was one of deference. “I’m at the end of my career. This is not about me. This is about America’s working families,” Walz told Harris and the vetting team, according to a person involved in the vice presidential vetting process who was granted anonymity to discuss the private meetings. “And if I...