What role for race in a U.S. general election?

ATLANTA (Reuters) - Some supporters fear Barack Obama's campaign to become U.S. president could be derailed by an old, familiar obstacle: race.

They cite evidence of racially polarized voting in primary contests as grounds for pessimism about the Illinois senator's prospects against Republican presidential candidate John McCain in November's election of a successor to President George W. Bush.

Their fears about Obama, who would be the first black president, are rooted in the history of a country where millions of Africans were once enslaved and today comprise around 13 percent of the population, but fare relatively badly across many social and economic indexes.

Blacks were denied the vote in the South until the mid-1960s, when they began to support the Democratic party and helped prompt a major political upheaval.

For example, when Sen. Hillary Clinton trounced Obama in Kentucky's primary on May 20, one-fifth of voters said race was a factor in their choice, and exit polls showed about 40 percent of her supporters planned to switch parties and vote for McCain in November if Obama became the Democratic nominee.

"It's sad that a lot of people can't bring themselves to vote for a black man -- and it's 2008," said Hannah Woodard, who voted for Obama in Covington, in northern Kentucky.

Kentucky exit polls echoed others in some other states where Clinton scored big wins, such as West Virginia, Ohio and Pennsylvania, all with large white working-class populations and all so-called swing states, whose influence is disproportionately great because their voters do not consistently back either political party.

As a group, voters in general elections are more white and more conservative than those in primary contests, which begs the question: Could Obama struggle in the general election because he's black?

"Many have said, 'if he is the nominee we will stay at home or vote for McCain.' It could be bluster or empty talk, but if any significant percentages vote for McCain it could be devastating for Obama's chances," said Earl Ofari Hutchinson, author of books on race and politics.

GENERATION GAP

Obama has done well in some states, including Alaska, where blacks represent less than 10 percent of the Democratic electorate.

That, coupled with his strong support from young voters and increased turnout and voter registration among black voters, could in some states offset any lack of support from whites and Hispanics due to race, Hutchinson said.

Several commentators cautioned against reading too much into polls about the impact of race on voting. They said it is difficult to project from primaries to a general election and noted that voter age, religious affiliation and education complicate efforts to determine the impact of race.

"It's not that he's black and they won't vote for him .... He's more culturally liberal, he doesn't have experience, he doesn't relate to them in a meaningful way," said Terry Madonna of Franklin and Marshall College in Pennsylvania.

But some commentators say Obama, 46, is more vulnerable to charges that he lacks patriotism and experience because he is young, and not white, and therefore less familiar to many voters.

"Because of his race, people more easily doubt his religious sincerity and his patriotism (and) .... charges that he is more style than substance are harder to deflect," said Mark King, a sociology professor at Morehouse College.

But in the end, the historic race involving the first black major-party nominee may come down to pocketbook issues, such as the economy, gas prices and health care costs, as well as the unpopular Iraq war.

The many policy similarities between Clinton and Obama accentuated ethnic and demographic divisions during the primary fight, but stark policy differences between the 71-year-old McCain and Obama will likely come to the fore in shaping voter sentiment in the race for the White House.

"It's not as though people are sitting around thinking: 'We really need a black president,'" said Melissa Harris-Lacewell, a politics professor at Princeton University.

(Additional reporting by Andrea Hopkins in Kentucky, editing by Patricia Zengerle)