by Philip Sherwell

Forty-five years to the day after Martin Luther King delivered his “I have a dream” speech, Barack Obama will become the first black man picked by a major party to run for president. Having picked Senator Joe Biden as his running mate, he is due to accept the Democratic nomination as their candidate in front of 75,000 supporters in Denver on Thursday.

It is a coincidence of dates not lost on Dr Gene Young, who - aged 12 - was among more than 200,000 civil rights supporters who heard Dr King spell out his hope for a future where people of all colours would live together harmoniously as equals.

“Obama’s nomination is a dream,” says the retired university professor. “I remember the protests, the police dogs and the fire hoses. I remember those who died in the fight to register black people to vote. I remember the church burnings. And now we could have a black president of the United States. I’m not just happy - I’m thrilled. I’m ecstatic.”

Despite his tender years and 4ft frame, Dr Young, now 57, was already a seasoned civil rights protester when he listened to Dr King’s famous address in Washington on August 28, 1963. By then, he had been arrested twice in his hometown of Jackson, Mississippi, the location of some of the ugliest incidents in the struggle for black rights in the Deep South. On the second occasion, he and his fellow detainees were held in the livestock pens at the city fairgrounds. “They thought we were no better than animals and kept us in the pens for horses and cows,” he recalls with a wry smile and shake of a head.

Those who had the temerity to challenge segregationist laws that treated African-Americans as second-class citizens faced arrest, violence or death. In one of the most notorious incidents of the era, three young activists - two white, one black - were murdered while investigating a church arson in a case made famous by the 1988 film Mississippi Burning.

Just two generations later, the son of a black man from Kenya and a white woman from Kansas is narrowly leading the polls in the battle to become the most powerful politician in the world.

Despite this dramatic progress, race remains a powerful but immeasurable factor in contemporary America. And as Mr Obama’s polling lead over his Republican rival, John McCain, narrows markedly, there are growing questions about whether skin colour is at play.

Given the country’s painful recent past, race is an issue around which Americans do their best to dance. Instead, it is being aired in surrogate language as questions are raised about patriotism and “American values”. And in the background, a virulent internet campaign promotes the stubborn fallacy that the youthful senator is a Muslim (substituting religion for race, with much the same effect).

“Race is the elephant in the living room here in America. Nobody wants to talk about it, but it’s a factor,” says Dr Young at his home in Jackson. “Racism is not as overt and obvious as it once was. We keep hearing that America wants a change - but does it want change enough to vote for a black man? We’ll learn that on election day. If he wins, I will die a happy man.”

Across the Pearl River, in predominantly white and rural Rankin County, there is anxiety rather than excitement about Mr Obama’s prospects. Among the hunters and anglers shopping for guns, crossbows, fishing rods and camouflage gear at the cavernous Bass Pro superstore, his race and religion are viewed with scepticism.

In opinion polls, about 10 per cent of Americans consistently believe that Senator Obama is a Muslim, because his father and stepfather were Muslim, his middle name is Hussein and he went to school for four years in Islamic Indonesia - even though he has attended a Chicago church for nearly two decades. Such views were easy to find at Bass Pro last week. “I’m afraid that if he wins, he will go back to his Muslim upbringing and change the country to reflect that,” says John McKellar, a 22-year-old gardener.

“He says he’s become a Christian but I’m not sure. His Muslim past and this talk about change worry me. He’s got a lot of support among African-Americans, but my friends are Christian church-going people like me and they all feel the same way.”

In another unpredictable twist to a highly unusual campaign, the first major accusation of the “race card” being played in the Obama-McCain showdown came from the Republicans and elicited a partial apology from the Democratic candidate.

Senator Obama had told supporters to expect a campaign of prejudice and fear from his rivals. “You know, ‘He’s not patriotic enough, he’s got a funny name.’ You know, ‘He doesn’t look like all those other presidents on those dollar bills.’ You know, ‘He’s risky.’ That’s essentially the argument they’re making.”

That produced a furious response from Team McCain. “Barack Obama has played the race card, and he played it from the bottom of the deck. It’s divisive, negative, shameful and wrong,” said top McCain adviser Rick Davis.

Discussing matters of race has always been a minefield in American political life, but those sensitivities have only heightened this year. The New Yorker magazine found itself at the centre of a row recently when it ran a satirical cover cartoon of Mr Obama dressed in Islamic robes and his wife as a black‑power activist.

Joke writers for late-night television hosts, for whom lampooning presidential candidates is staple fare, admit that they have been wary of taking cracks at Mr Obama’s appearance or style for fear they could be perceived as racist.

Yet even in his ethnic heritage, Mr Obama breaks stereotypes. Unlike most African-Americans, he is not the descendant of slaves. He spent his teenage years in Hawaii with his white maternal grandparents. Nor, at 47, is he a product of the civil rights era - also in contrast to most black politicians before him.

Indeed, in Chicago his exotic roots and Ivy League education meant he was viewed with suspicion by some in the black political community. Those doubts were eased by his marriage to Michelle Robinson, who hailed from a working-class South Side district, and his attendance at the church of Rev Jeremiah Wright, where many of the city’s black power-brokers worshipped.

So it is not without irony that those same links to Rev Wright have turned into one of his greatest political headaches - and will doubtless be highlighted as the presidential election on November 4 approaches and the campaign turns uglier.

Mr Obama came under fire from McCain supporters last week for another controversial Chicago connection that is being used to raise doubts about his patriotism. The advertisement highlighted his friendship with William Ayers, a former member of the Weather Underground, a militant far-Left group that bombed government buildings in 1970.

In the first months of his titanic primary campaign struggle with Mrs Clinton, Mr Obama was at great pains not to portray himself as an African-American candidate - with such success that some veterans of the civil rights movement even asked whether he was “black enough”.

But that strategy took a major knock in March when the Rev Wright affair transformed him, in the eyes of many, from a candidate who happened to be black into a black candidate. Mr Obama was thrown on to the back foot when some fiery sermons by his long-time pastor, spiritual mentor and black empowerment theologian emerged on YouTube.

The controversy forced Mr Obama to deliver what is widely viewed as his greatest speech in this campaign when he addressed the topics of race and religion in Philadelphia a few days later.

Yet since March Mr Obama has also increasingly lost the support of white working-class voters to Mrs Clinton in Democratic primaries in states such as Pennsylvania, Ohio and West Virginia. And all the indications are that he is still struggling to win them over to his cause.

According to a Wall Street Journal/NBC opinion poll last week, just 52 per cent of Clinton supporters in the Democratic primaries are currently backing Mr Obama, with 21 per cent switching party allegiances to Mr McCain and 27 per cent undecided. How many are motivated by the colour of Mr Obama’s skin is unclear, as voters are famously averse to telling pollsters whether race affects their choice.

Andrew Kohut, president of the Pew Research Centre, said one “real frailty” of polls on racism was that large numbers of people refused to take part in them.

“Are current polls accurate? I don’t know. This is something every pollster I know is concerned about,” he said.

Polls have regularly overestimated support for black candidates when it comes to voting day. The phenomenon has a name - the Bradley Effect - after Tom Bradley, a black Democrat who lost the 1992 Californian gubernatorial election despite surveys and even exit polls giving him a clear lead. Subsequent research showed that Mr Bradley had secured less white support than polls indicated. There was speculation that Mr Obama suffered from the Bradley Effect when he lost the New Hampshire primary, despite enjoying a large lead in most polls, and later polls in other states often exaggerated his final support.

Reflecting these findings, Matthew Dowd, chief strategist for President George W Bush’s 2004 campaign, said recently: “I wouldn’t want to be Obama and up two points going into election day. My guess is that the Obama campaign understands that and they know it’s not enough to be ahead - they have to be ahead by a lot.”

Even in this most unconventional of elections, Mr Obama’s name at the head of the Democratic ticket has thrown up one further highly implausible racial scenario. For some of the country’s most prominent white supremacists are backing a black man to become president because they believe his arrival in the White House will act as a “wake-up call” to America and bring new recruits to their cause. David Duke, a former Grand Wizard of the Knights of the Ku Klux Klan and self-described “white nationalist”, outlined that theory in a recent essay, “A Black Flag for White America”.

At his home in rural Mississippi, Richard Barrett, a champion of segregation and skinheads, made clear that he would be backing Mr Obama in November.

Although he declined to say how he would vote, he said he would cast a ballot on November 4 and it would not be for any of the other candidates. “Our goal is to radicalise America so we can achieve a new revolution,” explains Mr Barrett, leader of the Nationalist Movement and a lawyer who has advised Klansmen accused of murder.

“This country is facing the greatest conflagration in its history. I’m talking about an Obama victory, about the flag of New Africa replacing the Stars and Stripes, about the extinguishing of America and the American way of life.

“An Obama victory will revolutionise and energise the American people like never before. I think Obama is going to win and I think we will benefit from the backlash against that victory.”

Such views are increasingly marginal, however, even in modern Mississippi. More reflective of new realities was the scene at Pearl High School last week as black and white students, who will be 18 by November 4, registered to vote.

The Obama campaign’s priority across the South is to sign up young people and the black community - two of his key constituencies that traditionally have low voter-turnout - for the electoral rolls. Four decades ago, voter registration was a life and death affair in the Magnolia State. Now young volunteers are once again pouring into Mississippi in another great registration drive.

Dr Young is a passionate champion for that cause. “People lost their lives so we could enjoy the right to vote. So don’t insult me by telling me you’re not registered to vote. It’s the least we owe ourselves.”

Additional reporting by William Lowther in Washington