President Barack Obama is turning to black radio listeners to plead for midterm votes, a targeted approach to drum up Democratic support at a time when many candidates don’t want him around in person.African-American turnout will be vital to Democrats’ hopes in states such as Arkansas, Georgia, Louisiana and North Carolina that will help determine control of the Senate. And Obama remains beloved among black voters even if Democratic candidates in those races are running away from him amid the president’s low overall approval ratings. “This isn’t about my feelings being hurt,” Obama told the Rev. Al Sharpton in one...