Sean Trende seems to think so. Nate Cohn is skeptical:

Last November, Romney did extremely well among white voters, reaching about 60 percent of the white vote—the best Republican performance since 1988. Over the longer term, white voters have indeed shifted against Democrats: Obama did worse among white voters than Kerry, who did worse than Gore, who did worse than Clinton. As a result, Trende thinks it is “touchy to assume that the GOP will max out at 60 percent of the white vote,” which Romney scored last November, and he doesn’t “see a compelling reason why these trends can’t continue.”

But the GOP’s gains among white voters aren’t national. They’re almost exclusively among southern and Appalachian voters. Outside of the South, there’s no clear trend. And Democrats might have even made gains among whites outside of the South, both absolutely and with respect to the national popular vote.

Cohn argues that, to further increase its share of the white vote, the GOP will need to tweak its platform:

There is indeed room for the GOP to improve among white voters, but there’s no reason to think it won’t be painful, too. If Republicans don’t want to compromise on immigration reform, they will probably need to do something else to make up ground. It could be moderating on social issues or economics—or a little bit of both. Either way, the GOP will have to pick its poison.