This year's election promises to be one of the great experiments in U.S. history.
Is the country ready for an African-American president? No one knows for sure. It's increasingly clear, though, that the 2008 vote will be a referendum on the son of a black man from Kenya and a white woman from Kansas.
Inevitably, racial attitudes are going to influence that choice. But there is growing evidence that race is losing its potency as a determining factor in U.S. politics.
Some of it comes from a pair of statewide elections in 2006. Both featured breakthrough tries by black Democrats who, in effect, were trailblazers for Barack Obama. And top Obama strategists were involved in each one.
In Massachusetts, voters chose Deval Patrick as the state's first black governor. David Axelrod, a Chicago media consultant and Obama's chief adviser, worked in Patrick's campaign and has described it as a model for Obama's presidential run.
Like Obama, Patrick ran as an outsider and challenged what he described as the old politics. He convinced voters to think of his candidacy as an unconventional, Internet-based grass-roots movement that transcended race. (The linkage between Patrick and Obama produced some uncomfortable moments for Obama during the primary campaign, when similarities between language that both men had used - put in their mouths, presumably, by Axelrod - prompted charges of plagiarism.)
Patrick won in a landslide, after a general election campaign that resembled the one Obama is running against John McCain. He exploited the public's desire for change and tied his Republican opponent to an unpopular Republican administration in the state.
Becoming governor is not the same thing as gaining the presidency, however, and culturally liberal Massachusetts is not America.
Another statewide election that year, which has gotten less attention as a potential model for Obama, took place in Tennessee, where Rep. Harold E. Ford Jr. tried to become the first black elected to the Senate from the South since the 1800s.
Ford lost, but by less than 3 percentage points. The close finish sent a clear message: race was becoming less of an impediment for black candidates, even in the South.
The Democrat's defeat, according to officials of both campaign and independent analysts, had less to do with race than with issues of corruption involving members of his family and his background as a Washington insider.
"Saying race is not a factor at all is naive," said Dave Beattie, a Democratic pollster who conducted opinion surveys in Tennessee during and after the Senate contest. "It's that race is one of many factors that have to be dealt with."
Like Obama, Ford avoided making race the focus of the campaign, despite the news media's attention to it.
"This was not an issue he ran on. He never said, 'Let's make history,'" said Pete Brodnitz, who was Ford's pollster (and whose firm is the lead pollster for Obama's presidential campaign). "He was very clear that the election was not about race."
Republican candidate Bob Corker avoided direct racial appeals, but the issue was injected anyway.
Late in October, the national Republican Party ran an ad that attacked Ford for attending a Super Bowl party sponsored by Playboy magazine. In the ad, an attractive blonde cooed, "Harold, call me."
The ad was criticized as racially tinged and quickly became "a big distraction" that interfered with the Democrat's effort to communicate his message through the news media, his pollster said.
Paul Begala, a key strategist in Bill Clinton's rise to the presidency, said the attack on Ford contained "one of the most powerful messages that Republicans always try to pin on Democrats: [that] 'he's not one of us.'"
Attacks on Ford's relatives defined him in negative terms over something he had no control over.
"Perhaps the lessons of that helped Barack's team get him through the Jeremiah Wright" controversy, said Begala.
Obama responded with a speech about race and later dropped his membership in Wright's former church, but it's not clear that he's put the issue behind him.
John Geer, a Vanderbilt University political scientist, predicted that, just as in the Tennessee race, the "race card is going to get played," in some way, in the fall campaign.
The key "is going to be how Senator Obama handles it and how the news media handles it," he said.
"Racial appeals can often be quite powerful," he added, but they can backfire "if they're pointed out."
That's because racism has come to be seen, increasingly, as socially unacceptable, he and others said.
It is part of a gradual evolution, rather than a sea change, in voter attitudes. One element is generational.
"Twenty years ago, most voters had grown up in a society that was still legally segregated," said Beattie, the Democratic pollster. "But now, to have a recollection of that you have to be over 55."
Democrats are also making inroads in the suburbs, where voters "are basically beyond race. They're used to living in communities with a fair amount of diversity," Brodnitz said.
The suburbs are only one component, though. Rural areas, older voters and working-class communities pose more difficult challenges. Recent polling suggests that many voters still have doubts about Obama's background and values.
Votes that Obama will lose because he is black could well be offset by gains elsewhere, say Democratic and Republican strategists. These include new support from younger voters, Hispanics and blacks, as well as independent white voters impressed by his skills as a candidate and ready to take a chance on change.
In November, Americans will resolve the issue of whether someone other than a white man serves as president. But they might not answer the question of how racial attitudes influenced that decision.
"Somebody may say they are anti-Obama on the grounds of experience. Or they may say that he doesn't share American values because he doesn't wear a flag pin on his lapel," said political scientist Geer. "At one level, those may be legitimate concerns, but are they also a way to cover up racism? For some people, they may be; for others, not."
Sorting through the subtle factors behind voter choices, especially when race is involved, "is an absolute nightmare," he added. "A lot of people may be calling something racial when it's not. It's going to be very, very difficult to know."