Sen. Elizabeth Warren (D-Mass.) is defending her decision to release a DNA test and political ad asserting she has a distant Native American ancestor — even as the Cherokee Nation condemns her for it, Republicans mock her, and political analysts wonder if she has crippled any hopes she had of competing in the 2020 presidential election. “Donald Trump goes in front of crowds multiple times a week to attack me,” Warren told members of the Boston Globe editorial board Tuesday, referring to the president’s relentless mockery of a six-year-old accusation that the senator used to identify as a Native American...