Clinton's leading Trump by 4 points among college educated white people. Has this happened before in the last 50 years?
No. Ever since exit polls were introduced in 1952, Democrats have never won this demographic.
Although for comparison, Quinnipiac's last national survey in 2012 showed Obama leading with college-educated whites by a 5-point margin:
Ah so there is still a chance that some of these folks will go back to the republican camp. Trump cannot win without doing better among white people than romney.
Unless there is a huge surge of non college educated whites who have never voted before signing up just to support trump
