There is the Holy Ghost, for African Americans, and St Landry, for whites. In between is the cemetery where, by law and then by custom, people of the same faith have been buried separately according to their race.

In death as in worship the binary tradition of the south's racial history have persisted in deep southern states such as Louisiana. There is black and there is white and those basic differences will follow you to the grave and on to eternity.

But in the race for governor, which will be decided by elections on Saturday, the racial certainties inherited from slavery and perpetuated through segregation have become literally and metaphorically shaded by ethnicity.

In what is a tense and tightly fought campaign, the Republican candidate, Bobby Jindal, is neither black nor white but brown - the 32-year-old son of Indian immigrants. This in a state where 12 years ago a former grand dragon of the Ku Klux Klan, David Duke, won a majority of the white vote.

Yet Mr Jindal is close to breaking the mould with a victory that would strengthen the Republicans' grip in the deep south, following their governorship successes in Mississippi and Kentucky.

There is certainly nothing wrong with Mr Jindal's CV. With an ivy league education, the former Rhodes scholar was running Louisiana's medical system with a $4bn (£2.34bn) budget at the age of 24. At 27 he was president of the University of Louisiana system. By 30 he was the senior administration health policy official to the White House.

Look at his support base, however, and the fact that he is a contender in this state is little short of astounding. Standing outside the Charity hospital in New Orleans, his gangly, sloping frame is surrounded by the rosy cheeks and expansive girths of the southern good ole boys who make up the state's Republican leadership.

"He has amazed us in getting as far as he has," says Wayne Parent, the chairman of political science at Louisiana State University. "He's captured the biggest bloc of southern and Louisiana voters, rural social conservatives, and he seemed like the most unlikely to do that."

Ironically, Mr Jindal has leaned on the same core constituency as Mr Duke - white men, among whom, according to recent polls, he leads 61% to 35% over his Democratic opponent, Kathleen Blanco, the state's current lieutenant governor.

His campaign has even produced bumper stickers announcing "Bubbas for Bobby" (Bubba is an affectionate term for a southern white man).

Initially it was thought his ethnicity would be a significant obstacle. One black politician said of Mr Jindal's chances: "He's too dark for the white folks and not dark enough for the blacks." Warren Triche, a white Democrat, predicted Mr Jindal "wouldn't get as many votes in Acadiana [south Louisiana] as a mamou hoot owl".

The Indian community is right behind him. His victory would be of huge symbolic significance for one of the country's fastest-growing communities, even if most of them usually vote Democrat. "I disagree with him on many issues but it would be good for all of us if he won," said one Indian supporter, who did not wish to be named. "We are very proud of him."

But their support will make little difference at the polls in a state where they make up less than a fifth of 1% of the electorate.

Being Indian-American may set Mr Jindal apart from the traditional racial divide, but culturally he has long been well assimilated into Louisiana's particular brand of southern conservatism.

At the age of four he decided to swap his given name of Priyush for Bobby after a character in the Brady Bunch television show. At 18 he converted from Hinduism to Catholicism - unlike other heavily Protestant states this is a boon in Louisiana. At every opportunity Mr Jindal plays down his ethnicity as a factor and wraps himself in the flag.

"The voters of Louisiana are going to vote for the best candidate," he says. "It doesn't matter whether they are black, white, red or blue. We are all red, white and blue. We are all Americans."

Not even his own supporters believe this.

Harvey Thompson, an African-American Republican who is backing Mr Jindal, believes no black American candidate could have got the nomination for either party.

"A black candidate would never have got the endorsement of the present governor, he would never have got the resources to launch a campaign, and then white people would never have voted for him."

Mr Jindal joined the race late and took to the airwaves of rightwing talk radio, breathing fire with a slight southern drawl against abortion, divorce, big government, taxes and Jacques Chirac, over the war.

To hear him on the radio you would not know he was Indian unless the presenter brought it up. That might explain why he was the last major candidate to appeal for support on television.

The strategy of appealing to the Republicans' most conservative base worked. In the primary Mr Jindal topped the poll.

Louisiana holds an open primary where all candidates from all parties stand and if no one gets more than 50% the top two go through to a runoff. Of the 18 candidates standing, Mr Jindal won 33%. Ms Blanco, his nearest rival, won 18%.

Whoever wins will break Louisiana's mould. For all but 35 days of its 191-year history the governor's mansion has been occupied by a white man (PBS Pinchback, the son of a slave, was governor for little over a month in 1872).

Polls show both candidates have to take on prejudice within their core support base. While 23% of black men said they would be less likely to vote for Ms Blanco because she is a woman, 26% of blue-collar workers said they would be less likely to vote for Mr Jindal because of his ethnicity, according to the Marketing Research Institute.

"If his ethnicity damages his vote at all then it will probably be balanced out by the discrimination against her gender," Mr Parent says.

A lot is at stake. The primary issue in Louisiana, the only southern state recording a net outflow of people, is the brain drain and the economy. The state ranks in the bottom five in the country for poverty, unemployment and infant mortality.

But despite his initial victory, Mr Jindal remains a slight outsider. He may have come first in the primary but the combined vote of all the Democratic candidates was 57%. In the last week Mr Jindal has been catching up and they are now neck and neck.

In the crude racial arithmetic of southern politics Mr Jindal will have to secure 80% of the white vote and more than 15% of the black vote to win. The only question then is turnout and which candidate can best motivate their core base. So even though Mr Jindal's ethnicity has not become a huge issue, in a race as close as this any difference could be decisive.

Mr Jindal has received the endorsements of two black organisations that usually back Democrats. "He may make some incremental gains in the black community but I don't know whether it will be enough," Mr Parent says.

But Mr Thompson believes the underlying test will be whether his fellow white Republicans can overcome their traditional reluctance to vote for anyone other than a white candidate. "Some of them would rather have a white Democrat than a brown anything," he said.