Senator Barack Obama is refreshingly ambivalent about celebrity. Admittedly, he is said to be pals with George Clooney. Yes, he is raising money at LA fund-raisers attended by all the usual suspects. But the indications are that celebrities may not receive the respect from the Obama organisation to which they became accustomed in the salad days of the Clinton administration.

Led by Tom Matzzie, a liberal political operative who has been involved with some prominent left-wing efforts in recent years, the newly formed nonprofit group, Accountable America, is planning to confront donors to conservative groups, hoping to create a chilling effect that will dry up contributions.

In one of the most graphic ads, a “dissident” - with his arms handcuffed behind him - is depicted having his head dunked in a swimming pool by two “policemen”. The poster carries the caption: “After the Olympic Games, the fight for human rights must go on.”

In the ad, the 27-year-old heiress appears reclining on a sun lounger beside a swimming pool, dressed only in a skimpy leopard print bathing costume. “Hey America, I’m Paris Hilton and I’m a celebrity too,” she says.

Although Mr. Obama has been under an intense public spotlight for the last year, he is still relatively new on the national scene, and polls indicate that for all the enthusiasm he has generated among his supporters, many voters still have questions about him.

Senator McCain’s strategy is to leverage the adoring crowds and personal charisma that have created excitement around Senator Obama’s campaign and use this celebrity to raise questions about the Democrat’s political depth.