Romney won 59% of the white vote to Obama's 39%. Romney won a higher percentage of the white vote than Reagan, but the size of the white vote in 2012 was much lower than when Reagan ran.
This trend will continue. The size of the white vote will continue to fall and the size of the Hispanic vote continue to grow.
The 2016 GOP candidate can still win on the white vote but he will need to win a larger percentage of the white vote than Romney did.
Hispanics are not evenly distributed. They are congregated in NV, CA, TX, AZ, FL, NJ. Florida is the pivot point in Presidential elections and if the GOP candidate doesn't win FL, he can't get elected. So the Hispanic vote in FL is most important. There are 4 groups of Hispanics in FL: Cubans, South Americans, Mexicans, and Puerto Ricans(growing the fastest).
The “Hispanic vote” will only continue to “grow” if we allow the invasion to continue. Most of us realize we would be suicidally stupid to do so.