( dpa ) - As South Carolina Democrats prepared to vote Saturday, Senator Barack Obama held about a 10-percentage-point lead over Senator Hillary Clinton in state polls for the centre-left party's presidential nomination.
Former senator and 2004 vice-presidential nominee John Edwards, 54, a native South Carolinian, was moving up in the polls after a strong performance in a debate earlier this week but still trailed in third place.
The vote in South Carolina will mark the first Democratic contest in the US South and the first presidential primary not being played out before an overwhelmingly white electorate - about half of the state's 2.5 million eligible voters are African-American.
Republicans voted last week in South Carolina, giving Senator John McCain, 71, a close victory.
To date, Obama, 46, has claimed one primary victory in Iowa, while Clinton, 60, has claimed New Hampshire and Nevada. Obama had been favoured going into the New Hampshire vote, but Clinton surprised pollsters and pundits by taking the state.
Competition in South Carolina is stiff, as all three remaining Democrats seeking the 2008 nomination make unique claims to represent the interests of the South.
Clinton, trying to become the first woman president, spent eight years as first lady in Arkansas, another Southern state, when Bill Clinton was governor. Her husband, who later rose to the White House, was described by some as the nation's first black president because of his popularity among black voters.
Obama, who hopes to become the country's first African-American president, has placed "change" from conventional Washington politics at the heart of his campaign and portrayed himself as a candidate who can transcend the issue of race.
In addition to having been born in the state, Edwards was elected to the US Senate from neighbouring North Carolina and won South Carolina in his 2004 bid for the Democratic presidential nomination. He has made ending poverty a lifetime goal that plays well in the poorer, Southern states, and even launched his candidacy last year from the impoverished New Orleans quarter that was among the worst- flooded by Hurricane Katrina.
National polls show Obama leading Clinton among black voters. Clinton leads among white voters, women and overall in the Democratic Party ahead of the crucial, so-called Super Tuesday on February 5, when more than 20 states will vote in primaries that could be enough to decide the nomination.
Race and to a lesser extent gender are the latent issues in the 2008 Democratic nomination battle. The issues reared up in a bruising tussle last week between the Clinton and Obama camps leading up to South Carolina, as Clinton was criticized for comments some viewed as belittling the work of martyred civil-rights leader Martin Luther King Jr.
On Tuesday, centre-right Republicans will cast presidential preference ballots in Florida.
The candidates are competing for delegates to nominating conventions in August and September before the November 4 general elections.