The nation's first black president could be in danger of becoming a "one-termer" if he can't convince enough white voters that he deserves another four years in the Oval Office.

For weeks, he's hovered around 40 percent of white voter support -- a level that Democratic presidential candidates have struggled with in the recent past and one that analysts believe Barack Obama must maintain in order to win. At the same time, he has to encourage minority voters to go to the polls and capture 80 percent of their support.

"Obama in '08 became the first presidential candidate ever to lose whites by double digits and win. And he could lose them by even more this time and still win. But he can't fall through the floor with them, and the polling shows him ... right at the water line of 40 percent that he'll need, maybe just below sometimes just above," said Ron Brownstein, the National Journal editorial director and CNN senior political analyst.

"The big qualification: he's running better among working class whites in the upper Midwest battlegrounds of Iowa, Wisconsin and Ohio than anywhere else and that is his last line of defense in this very close election," he said.

With 59 percent support among whites, Republican presidential nominee Mitt Romney is hitting record numbers among that group. He is approaching a margin of support last seen by Republican Ronald Reagan in his 1984 re-election.

Yet, support for Romney among non-white voters has hovered between 18-20 percent, according to national Washington Post-ABC News tracking poll data.

During his 2008 presidential campaign, Republican nominee John McCain got roughly 55 percent of the white vote and 20 percent of the non-white vote.

"This is a long-term demographic problem," John Avlon, a CNN contributor, said. "We don't want to see our politics divided by race going into the future. That is not healthy or sustainable for a nation as large and diverse as we are and this election is shaping up along these fault lines."

The racial trends in this year's election are part of a complicated calculus in which a greater number of white Republican voters could offset possibly lower turnout among the Democratic base of minorities and young voters.

Moreover, an ongoing fight in battleground states over voter identification laws, which some opponents say are efforts to disenfranchise minority voters in a close election and proponents say are needed to prevent fraud, is also a factor.

The result is a deeply partisan and polarized election that could hinge -- in part -- on some uncomfortable racial math.

"Part of the reason we're thinking about this is the dynamic of this being a black president," said Mark Anthony Neal, a cultural and Black studies professor at Duke University.

Neither the Obama and Romney campaigns commented on the racial differences in the polling figures.

However, both campaigns have shown that they are aware that the nuances of race factor into potential wins.

Romney's comments during a May fundraiser that "it would be helpful to be Latino" because were he "born of Mexican parents, I'd have a better shot of winning this," went over poorly with some Latinos---a voting block the campaign is trying to make inroads with through Spanish language advertisements and dispatching bilingual surrogates.

During recent comments to the Des Moines Register editorial board, Obama said: "I will just be very blunt. Should I win a second term, a big reason I will win a second term is because the Republican nominee and the Republican Party have so alienated the fastest-growing demographic group in the country, the Latino community."

Obama made history when he won the 2008 presidential election --- a feat he accomplished in part with 43 percent of the white vote. It was the same percentage former President Bill Clinton netted in 1996.

But Democrats have struggled for the past decade to hold on to white voters during presidential elections, Brownstein said.

In 2004, Sen. John Kerry lost his presidential run after getting only 41 percent of that group. In the 2000 election, Vice President Al Gore lost with 42 percent of the white vote, 90 percent of the black vote and 35 percent of the Latino vote.

"Democrats have struggled for several decades to maintain any measurable level of support among whites, especially non-college whites," Brownstein said.

"No Democratic nominee has won a majority of whites since 1964. And it's been especially hard for Democrats to hold onto whites after they have had unified control of Washington, which suggests they are having trouble convincing whites to buy into their vision of activist government."

And Republicans have struggled to woo minority voters.

In 2004, for example President George W. Bush won re-election with 30 percent of the minority male and 24 percent of the minority female vote. Exit polls from the 2000 election showed that Bush received only 9 percent of the black vote and 35 percent of the Latino vote.

The number of minority voters has increased since those elections. Over the next several generations, the wave of minority voters -- who, according to U.S. Census figures, now represent more than half of the nation's population born in the past year -- will become more of a power base in such GOP strongholds as Alabama, Mississippi and Georgia. That hold will extend all the way to California, experts say.

But for now, the population remains majority white and turnout rates are traditionally lower among minorities -- both factors that could prove problematic for Obama.