Recent polls showing Vice President Biden or even Senator Sanders defeating President Trump in a general election are understating Mr. Trump's true strength. An Emerson College poll released April 15 had Mr. Biden beating Mr. Trump 53% to 47%, and Mr. Sanders beating Mr. Trump, 51% to 48%. A Morning Consult Politico poll released April 24 had the ex-vice president at 42% and Mr. Trump at 34%. A Hill HarrisX survey released April 26 had Vice President Biden at 43% and President Trump at 37%...
