Hillary Clinton has abandoned hopes of winning South Carolina and is instead focusing her energies on Super Tuesday battlegrounds as latest polls show Barack Obama with a seemingly impenetrable lead ahead in the state ahead of Saturday’s primary.

Mr Obama, Mrs Clinton’s main rival in the race for the Democratic presidential nomination, holds a hefty 18-point lead over the former first lady three days ahead of the pivotal contest, according to a Reuters/C-SPAN/Zogby poll released today.

His prospects have been significantly boosted by the huge edge he now commands among African-Americans, who make up more than half of Democratic primary voters in South Carolina.

The young Illinois senator leads Mrs Clinton Obama 43 per cent to 25 per cent in the rolling poll, with John Edwards, who had hoped to capitalise on his South Carolina roots, trailing a distant third at 15 per cent. The poll has a margin of error of 3.4 percentage points.

Mr Obama, who would be America’s first black president, leads among African-Americans by 65 per cent to 16 per cent. Mrs Clinton and Mr Edwards are virtually tied among white voters, with Mrs Clinton leading 33 per cent to 32 per cent, while Mr Obama is third among whites at 18 per cent. Likely black voters make up slightly more than half of the poll sample.

“Obama is doing very well among African-Americans but getting a decent share of the white vote in a three-way race,” John Zogby, the pollster, commented.

However the results also show how effective Mrs Clinton has been in marginalising Mr Obama as a minority candidate. Originally considered the first African-American contender with broad appeal across all ethnic groups, Mr Obama was in fact less popular among black voters than he was among the affluent, young white voters who constituted his base. Now, in the wake of the bitter civil rights row sparked by Mrs Clinton’s comments on the role of Martin Luther King in bringing about equality, Mr Obama’s support among African-Americans has solidified while his support among whites has begun to wane.

The increasingly vicious battle between the two frontrunners continued yesterday as the pair traded cross-country blows from their campaign stops in South Carolina and California, where Mrs Clinton is now concentrating her efforts. She accused Mr Obama of launching pre-planned attacks against her in Monday’s South Carolina debate to disguise inconsistencies in his own record, while Mr Obama accused her of flip-flopping on issues such as free trade.

A new Field Poll of likely California Democrats and non-partisan voters yesterday gave Mrs Clinton a solid 39 to 27 percent lead over Mr Obama ahead of its February 5th primary. As the most delegate-rich state, harvesting its 370 convention votes could propel her into an almost unbeatable position, particularly if Mr Obama fails to repeat his stunning Iowa victory in South Carolina and some major Super Tuesday states.

She is leading three-to-one among Latino voters, two-to-one among lower income groups and two-to-one among women - a similar demographic profile to those which helped her to victory in the recent Nevada and New Hampshire nominating contests.

As a sign of the importance she is placing on the state, Mrs Clinton made a 20-hour, 5,000-mile trip from Washington yesterday to pick up the endorsement of a national farm workers union. She left her husband, the former president Bill Clinton, to slug it out with Mr Obama in South Carolina while she later swung through Arizona before heading back to the US capital.

Though she insisted that it was unfair to say she had abandoned South Carolina to focus on battles to come, she is not planning to visit the state until later this week, with New Jersey, one of the 22 states holding contests on Super Tuesday, on her schedule for today.

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