UNITED STATES: Which Democrat has the best shot against McCain?

POLLING:

Opinion polls by CNN, Time and AP tell the same story: In a match up with John McCain, Hillary Clinton is either level or slightly ahead. Barack Obama is six to eight points ahead of McCain. In Obama's case, there have been several examples in the campaign of polls over-estimating his support. Still, at this stage, he has the edge.

POSITIVES:

Barack Obama:
Obama has charisma, the ability to inspire people and general likeability. He has a calm, authorative, here's-the-deal manner that inspires confidence. His electrifying speechifying - in a easy-on-the-ear baritone - is without peer. He makes people feel good ... and feel good about voting for him.

His endorsement by members of the Kennedy family spawned comparisons to JFK. - who was younger but far more experienced than Obama when he became president - but a more relevant comparison is probably with Tony Blair when the former British Prime Minister was first elected.

Like Blair then, Obama transcends tribal politics, attracting non-party loyalists, independents and even some Republicans. Like Blair then, he defies easy categorisation in his background and approach. Initially, he struggled to draw party loyalists, relying heavily on independents and new young voters.

His call for change and arguments that he is the most electable and that only he can get Washington working is reminiscent of Blair's positioning himself above his party. Obama, like Blair then, presents himself as apart from the problem - unlike the 'old school' Democratic politicians and activists. Obama's message of unity, manners and Blair-like crisp, rather corporate appearance, reassures many centrists.

He has lured a lot of new voters. Even though his record suggests he's hardly a radical, he would still represent an intoxicating plunge into the unknown. The Kennedy endorsement helped Obama cast his candidacy in historic terms: Voters, catch this moment in time.

Obama has tried to turn his 'freshness' into an advantage, pouring scorn on those who say he needs to be "seasoned" in Washington until hope and idealism have been drained away. No wonder that appeals to younger voters - it chimes with a younger person's view of the world where more is possible and experience is less important. But, as Newsweek has pointed out, it also points to an attempt to paint US politics in Democratic hues, breaking the shackles where conservative ideas have been in ascendency. Obama tries to link Clinton to McCain and Bush - arguing against electing a cautious president unable to move far from centrist, Republican, positions.

Hillary Clinton:
Clinton's negatives are, in a way, part of her positives - for this election she's the devil you know, a pair of safe hands for those who want change from the Bush Administration ... but not too much. Her pitch is her experience and clear-eyed, dogged toughnness. Voters expect her to push hard to get programmes implemented and to deal with foreign policy in a pragmatic, realistic way.