Minnesota Gov. Tim Walz is giving his first speech Tuesday evening as Vice President Kamala Harris' running mate. The two appeared together at a rally in Philadelphia. Walz began his remarks thanking Harris for selecting him. But the campaigner known as being upbeat said, “Thank you for bringing back the joy!” He then noted his wife, a 29-year public school teacher, wryly plugging a key constituency, “Don’t ever underestimate teachers.”