"What we're beginning to see is the Republicans are becoming increasingly white and Democrats are increasingly losing white people. They're maintaining the minorities, but losing whites ...," CNN contributor LZ Granderson told the network. "It's the message. Something they're doing as a party that is not appealing to the white voter. And so it isn't just about President Obama. It's about the platform."

Political experts attribute part of Obama's struggles with some white voters to disappointment in his handling of the economy.

Discomfort over his shift on such social issues as support for gays serving openly in the military and his administration's federal mandate requiring religious institutions to offer employees insurance coverage for contraception may keep some socially conservative white voters from casting ballots for Obama, political experts say.

But for some voters, a subtle form of racism may also be at play, Neal said.

"If we were in a post-race society, the measurement is not the election of Obama but the re-election of President Obama. He still had to perform and he has been held on a short leash in that context," Neal said making the analogy that black professional sports coaches and managers are similarly given less room to stumble than their white counterparts.

"Many voters including black voters don't feel Obama performed exceptionally (on the economy)," Neal said. "So much of what we've seen in terms of Romney support is a fundamental distrust of Obama because he's not giving the goods. That argument is easier to be made because he's black. ... It's not so much they are voting for Romney because he's white but the economy protects them. They don't have to feel guilty because of the economy. The economy lets them off the hook."

Whatever the reasons for the gap, Obama will have to work overtime to maintain numbers of white voters who say they will vote for him while convincing minority voters to turn out to vote, said Andra Gillespie, an associate professor of political science at Emory University.

"To be more comfortable he should be going above 40 percent (with white voters)," Gillespie said. "He's focusing on women, the majority of whom are going to be white, by talking about issues of reproductive health and contraception. He's going for the white youth vote by talking about student loans."

Both campaigns realize that all of their careful math hinges on getting out the vote.

"They should have a good sense of where their voters are and who their voters are. They should have spoken to them by phone," Gillespie said. "And they should have a plan in place to ask them to vote between now and Election Day."