Sitting at a lunch counter in the shadow of Roanoke Rapids' shuttered textile mill, Beverly Joyner summed up the attitudes of a large number of North Carolina's rural white voters. “It's going to be a hard decision.”

Tuesday's Democratic primary is the first meaningful contest of its kind in North Carolina since 1988. The controversy surrounding the Rev Jeremiah Wright, Barack Obama's former pastor, has left working-class whites with serious questions about Mr Obama's fitness to lead and his electability in November's general election.

Roanoke Rapids is in the agricultural east of the state. It is an old mill town whose industrial heart has been largely destroyed. Struggling to redefine itself in the post-industrial economy, this is “God and guns” country where Hillary Clinton should do well in Tuesday's election, at least among the 75 per cent of white voters.

Many people from North Carolina, myself included, approach the subject of race with caution. In America's South, where racial conflict was once a way of life, overt racism is rarely accepted in polite company. Instead, the subject of race comes disguised as other issues. Having grown up as a white male in North Carolina, this phenomenon is all too easy to identify.

This week I spoke to several voters who expressed concern over Mr Obama's ability to reunite the Democratic party and the country should he be the party's nominee. While clearly masked, it was not difficult to see that their misgivings had more to do with race than they may have been willing to admit. For Mr Obama, questions about his electability and references to Mr Wright are often examples of this vast racial undercurrent.

Gary Pearce, a veteran political strategist, put it more bluntly: “It's all about race. It's always that way in North Carolina, especially with a black candidate.” As polls have narrowed over the past weeks Mr Obama is losing ground. Having once held leads as high as 23 points, Mr Obama is now facing the prospect of a single-digit win. Coupled with a loss in Indiana, such a small margin could be a sign of serious trouble for his campaign.

Perhaps more meaningful than the margin of victory, polls show white and black voters sharply divided in their preference for Tuesday's election. Mr Obama is performing at almost 90 per cent among the state's black voters while Ms Clinton leads among white voters by more than 30 per cent. Given the expected black turnout in a state where 22 per cent of the population is African-American, the story out of North Carolina may be that Mr Obama wins, but underperforms yet again among white voters. This seeming inability to win over working-class whites, the traditional core of the Democrat Party, has plagued Mr Obama in states such as Ohio, where he lost among white voters by nearly 30 per cent.

Dave “Mudcat” Saunders, a political strategist, blames Mr Obama's weakness among rural, working-class whites on his ineffectiveness in appearing to care about the issues that matter to them. “Who in the hell thought Hillary Clinton could be the pro-gun, anti-trade candidate,” he said.

Steven Greene, Professor of Political Science at North Carolina State University, agreed, but believes that it's more about what the candidates are saying. “She is talking about concrete ideas, while he's talking at a more abstract level, and rural white voters need the benefits of her proposals.” He added that, for these voters, opinions are often “driven by race, but not necessarily racist”.

Tony Perry, an African-American real estate developer, is supporting Mr Obama but believes that Mr Wright has done him a lot of harm among white voters in North Carolina. “Rev Wright scared a lot of people, including some in the black community.”

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