Baseman here is why Obama resulted in a greater racial divide. Rich whites sold poor whites a bill of goods which said that even though they are poor, at least they are white. So deserve white privilege.
Along comes Obama and his very well educated and sophisticated wife and daughters. They look at their drug addicted kids and suddenly realize that they aren't better than blacks.
So they want THEIR America back again. Well the truth is that they NEVER had it. A history of white poverty in areas where support for the GOP is strongest showed that before the LBJ reforms destitution was rife. Even today the greatest concentration of white poverty remains in areas which support the GOP!