One segment of whites with whom Obama did well was young people. He won backing from half of white voters under age 30, with Clinton and Edwards splitting the rest. Young white voters, however, made up only about one-twentieth of those who voted Saturday.

Racial attitudes were also in play in voters' perceptions of how effective the candidates would be if elected. Whites were far likelier to name Clinton than Obama as being most qualified to be commander in chief, likeliest to unite the country and most apt to capture the White House in November. Blacks named Obama over Clinton by even stronger margins — two- and three-to one — in all three areas.

Following a week of criticism between the Obama and Clinton campaigns in which race became a factor, Obama's relatively small share of white supporters in South Carolina could raise questions about his ability to attract those voters in the crucial Super Tuesday contests on Feb. 5, when nearly half the country will vote.

Because of his heavy support from blacks, Obama negated the advantage Clinton has enjoyed among women in most of this year's contests. He got more than half the female vote, compared with three in 10 supporting Clinton, the New York senator.

But the gender breakdown was heavily affected by race. Though Obama won eight in 10 votes of black females, Clinton and Edwards led among white women, getting about four in 10 of their votes, about double Obama's share.

Edwards, the former North Carolina senator, led among white men, garnering about four in 10 of their votes, with Clinton and Obama about equally sharing the rest.

In a race featuring candidates who would be the country's first female or first black president, about three-quarters of Democrats said they thought the country was ready for either historic event to occur. And in a show of general Democratic satisfaction with their choices, more than eight in 10 overall said they would be satisfied if Obama were the nominee, while about three-quarters said the same about Clinton.

Bill Clinton's campaigning in the state — in which he engaged in some of the campaign's sharpest attacks on Obama — was cited as an important factor by nearly six in 10 voters, including about equal amounts of blacks and whites.

Overall, those who said it was important voted in favor of Obama, though by smaller margins than those who said it was unimportant, suggesting his effort may have helped Hillary Clinton slightly.

As has been the pattern in most of the Democratic contests this year, the economy was cited as the most important issue facing the nation by far, with about half naming it. About half of those voters backed Obama and about three in 10 supported Clinton. Obama had an even bigger edge among voters naming health care or the war in Iraq as the top problem.

In another replay of Democratic sentiment from other states' voting, about half said they wanted a candidate who can bring change, making it the most sought-after quality. And once again this was dominated by Obama, who has made it the leading theme of his campaign, as he won three in four voters who named it.

Obama and Edwards about evenly split the lead among voters who said they wanted a candidate who feels empathy for people like them. Clinton, as she has done in the past, won easily among those favoring experience, but they were a small share of voters, fewer than one in five.

The poll was conducted for AP and the television networks by Edison Media Research and Mitofsky International as Democratic voters exited 35 sites in South Carolina. The poll interviewed 1,905 Democratic primary voters and had a margin of sampling error of plus or minus 3 percentage points.