A look at 2012 Demographics

Myself and others speculated that if the GOP won white voters by about 20 points or more, that would offset any gains for Democrats from white turnout being held at 2008 levels (when they made up 74% of the electorate). And indeed, Romney performed much better among white voters than John McCain four years earlier, winning the largest voting block 59-39%. McCain only carried the group by 12%.

But what many did not count on (myself included) was a full 2% drop in the number of white voters in the electorate. That, coupled with 2008-like African American turnout, increased Latino turnout, and a stronger Obama margin with Latinos led to Romney's demise.