That’s a pretty big problem no matter who wins the GOP nomination. And they are quite aware of it. Their strategy is to grow the white vote, to turn out even more white voters than they did in 2012, because they figured there were 7 million fewer white votes in 2012 than there was in 2008.
The problem with this approach however, is that Romney captured more of the white vote than Reagan did, yet still lost by almost 4 points. If we only change the votes based on demographic changes, Romney loses by almost 6 points in 2016.
And Hillary will probably capture a bigger percentage of the white vote than Obama did (white non college voters, of which Romney won, will decrease by 1% by 2016…white college voters, of which Obama won, will increase by 3%). So even getting out the white vote is actually harmful to them at this point; its only the non college educated white voters…and when you start slicing up the voter segments that small to try and compensate for losing every one else, you are definitely in a death spiral.