That's a big "if."
Still, an Associated Press analysis of U.S. Census and voting data from the past four presidential elections shows a potentially dramatic impact should Obama fulfill his pledge to elevate black participation by 30 percent.
That would add nearly 1.8 million votes in 11 Southern states, the analysis shows, enough to tip the balance in several that have been Republican strongholds.
Besides the likely increase in black turnout, the Illinois senator also expects a surge of young voters to help him compete in states that have been reliably red since the once solidly Democratic South flipped to the Republicans in 1964.
"I can tell you that North Carolina, South Carolina, Georgia and Alabama will be in play," asserts North Carolina Democratic Rep. G.K. Butterfield, an Obama adviser. "We're looking strongly at Tennessee and Mississippi."
Obama set the 30 percent goal himself last August at a campaign stop in New Hampshire.
"I guarantee you African-American turnout, if I'm the nominee, goes up 30 percent around the country, minimum," he said. "Young people's percentage of the vote goes up 25-30 percent. So we're in a position to put states in play that haven't been in play since LBJ."
The math backs up his analysis - if he can deliver the turnout he promises. In Georgia, the GOP presidential nominee's average margin of victory in the past four elections was 216,000 votes. If 30 percent more voting-age blacks go to the polls in November than the four-year average - with all else equal, and Obama capturing all of those votes - he would win the state by 84,000 ballots.
Should 90 percent of those voters go for Obama, a figure he achieved among blacks in some primaries this year, he would still have enough to win the state and its 15 electoral votes.
If Obama reached his goal of a 30 percent increase and brought all those new black voters into his fold, he could also win in Arkansas, Louisiana, Tennessee, Virginia and Florida. Wins in the six states would give him 81 new electoral votes - enough to beat Arizona Sen. John McCain even if the Republican won almost every other toss-up state in the nation, including Michigan, Pennsylvania, Missouri and Ohio.
A 30 percent boost in black turnout also could pull Obama into a tie with McCain in Mississippi. And in South Carolina, a conservative state that went to President Bush by 17 percentage points four years ago, Obama could come within 17,000 votes - less than a percentage point. Ditto in North Carolina, a state often mentioned as a possible Southern pickup for Obama.
Tom Schaller, a University of Maryland political science professor who has long argued that Democrats don't need to win the South to win the White House, said a 12 percent increase in black turnout across the region would be enough to swing Virginia, Florida and perhaps another state.
But he's not sold on Obama's guarantee.
"I'll believe a 30 percent increase in the black vote when I see it," Schaller said. "If Obama does it, he will have proved to doubters like me that his organizing skills in Chicago coupled with his vision and charisma are truly transformative. It'll be a thumping on Nov. 4."
Obama's advisers admit they have a distance to go.
In four Southern states that were able to provide figures by race - North Carolina, Alabama, Georgia, and Louisiana - the number of registered black voters has risen 12 percent since the beginning of 2006. That's a remarkable run, and one that could be further buoyed by an increased turnout among blacks already registered. But white turnout has been up, too.
Also, there's no way Obama will win all black votes, even in this history-making election as the first black candidate on a major-party ballot. About 11 percent of black votes went to Bush in 2004, though that figure is expected to decrease substantially in this year's race between Obama and McCain.
And there is no guarantee that Obama will keep the support of all Democrats who voted for John Kerry, Al Gore and President Clinton in the previous three elections. An AP-Yahoo News election survey has found that 8 percent of all whites say they would be very uncomfortable voting for a black presidential candidate, and even 16 percent of Democrats say they would have at least some reservations.
"It would be an important change in the dynamics of Southern politics if Obama reached his goal of increasing black voter turnout by 30 percent," said Ferrel Guillory, who tracks Southern voting as director of the Program on Public Life at the University of North Carolina at Chapel Hill. "But he probably can't win simply with that. He's still got to be attractive to white voters."
There are important other factors sure to affect whether this year's vote follows the trends of past elections.
McCain's history of bucking Republican orthodoxy could draw moderates to the GOP. On the other hand, 25 percent of voters who call themselves "very conservative" are either backing someone other than McCain or remain undecided, the AP-Yahoo News election survey shows.
As for Obama's registration drive, in North Carolina's Durham County, where 38 percent of residents are black, local Obama organizers boast a volunteer roster of 4,700 people - equivalent to about 2 percent of all people who live in the city of Durham.
Faulkner Fox, a local leader for Obama, said the group's members, both black and white, are registering voters at a pace she hasn't seen in 20 years of organizing.
Still, experts wonder. David Bositis, who tracks black voting trends for the Washington-based Joint Center on Political and Economic Studies, says the primaries showed "there is something going on in terms of black voters already. There's evidence they're charged up for this election." But he also said he's more comfortable predicting a turnout increase of 20 percent.
McCain's campaign so far seems comfortable with his chances to continue the GOP's success in the South. The Arizona senator is setting up a campaign organization in Virginia and is considering doing the same in North Carolina. Other staffing decision are to be determined, advisers said.
"I certainly don't fault Sen. Obama for trying to put some states in play that haven't been in play in the past," said Mike DuHaime, who advises both the Republican National Committee and the McCain campaign. "It's probably a smart political move. I don't think it will pay off in terms of electoral votes."
