MANCHESTER, N.H. — Joe Biden has had enough of Pete Buttigieg’s malarky and, folks, he’s about to show that young whippersnapper a thing or two about running for president. In a series of post-debate appearances, a meandering press conference and a withering new attack ad, Biden struck back at the South Bend upstart’s call for a new generation of leadership and wrapped himself in the legacy of former President Barack Obama. It’s all part of the former vice president’s new, and somewhat uncomfortable, campaign trail look: Scrappy underdog. “I have never been very comfortable attacking somebody else. I don't think...