By Clare Murphy
BBC News Online
Sammy Davis Jnr, one of his biographers once observed, was Richard Nixon's envoy to black America - a world the president did not understand.
"I'm listening": Frasier backs George W Bush
For the part of the famed Rat Packer, the decision to campaign for a president whom many blacks despised was driven by raging insecurity and the desire for acceptance, according to Wil Haygood, author of In Black and White: The Life of Sammy Davis Jnr.
The bulk of shoulder rubbing between celebrity and politician in the US is rarely so complex, nor subject to such psychoanalysis.
But the intermingling of stars and politics has been a staple of American public life for the past 80 years - starting in the 1920s, when Al Jolson led a delegation of 50 Broadway actors and actresses to a rally in support of Republican candidate Warren Harding.
More recently, Bush bashing has become a favourite pastime of the often left-leaning celebrity elite - few award ceremonies are complete without an outburst.
It comes thus as little surprise that as presidential elections loom, the stars are out in force in the hope of giving the Democrat candidate, John Kerry a well-manicured helping hand.
Even the organiser of two Democrat celebrity fundraisers concedes he has been surprised by the level of interest in taking part in the events.
"I've never seen this before - how ready everyone was to show up and work," said Jann Wenner, editor of Rolling Stone magazine.
Barbra Streisand, who has rewritten her hit People to include the lines: "We must get rid of Rumsfeld/He's the spookiest person in the world," was among the more usual suspects at the first concert at the end of June. The singer has long campaigned for the Democrat cause - and indeed, made it on to Nixon's infamous "Enemies List".
But a host of others also paid up to show their support for Mr Kerry, including Neil Diamond, Ben Stiller, Robert De Niro and Leonardo DiCaprio. Adding a personal touch, the actor Ben Affleck declared: "I know the man!".
Some of the celebrity endorsers - while keen to present themselves as not just anti-Bush, but crucially, pro-Kerry - have only flocked to his camp since he secured the nomination, trouncing preferred candidates such as Howard Dean.
Jon Bon Jovi has also been lending a helping hand
But this is not a time to be fussy about friends in high places.
One of the crucial elements of celebrity endorsement is cash. The June event raised some $5m for the Kerry campaign. The second concert on Thursday will feature Jon Bon Jovi, Mary J Blige and the Dave Matthews Band, among others, and has similar sums in the picture.
"But it's also about glamour," says Alan Schroeder, author of Celebrity-in-Chief: How Show Business Took Over The White
"John Kerry is not Bill Clinton, and so rubbing shoulders with these people allows him to bask in some of their shine."
Mr Kerry is not the first presidential contender to borrow from celebrity to make up for some perceived deficiency.
George Bush Senior for example, sought to beef up his image by befriending action heroes such as Arnold Schwarzenegger and Bruce Willis. Tom Selleck, alias the cunning and dashing Magnum PI, added brains to the brawn.
But does it work?
The combined charms of Selleck and Willis were not, however, enough to secure Mr Bush's re-election.
But his son, the incumbent president, is one of few prominent politicians to acknowledge that he has benefited from celebrity ties.
The one-time owner of the Texan Rangers baseball club noted - albeit in a somewhat tongue-in-cheek fashion - that he would not have won the Texan governorship were it not for his association with Nolan Ryan, one of the club's stars.
Overall however, George Bush Jnr has not been overwhelmed with celebrity endorsement, although he can count the actor Kelsey Grammer - alias radio psychiatrist Frasier - as a fan.
Republicans have long found it more difficult to win celebrity backing - and in terms of raising money, have less impetus to do so.
And despite the modern obsession with celebrity, there is little evidence to suggest that having stars on board actually changes people's minds.
Nonetheless, aside from the cash they contribute, one of their key uses is to secure airtime, and drum up interest among those who might otherwise not be engaged.
In a close election, their ability to bring out even a marginal amount of votes could mean the difference between winning and losing.
No free lunch
There are risks, however.
At the very least, too much hobnobbing with celebrities, or "limousine liberals" as they are sometimes called, can make one seem rather shallow, and indeed out of touch.
Nixon wanted to keep his meeting with Elvis secret
On top of this, the stars do not read from approved scripts; what is thus intended as a friendly, helpful speech can sometimes prove a political minefield for a candidate.
An oft cited example is that of the film director Michael Moore, who after backing former Nato commander Wesley Clark for the 2004 Democrat nomination, accused President Bush of being a deserter.
General Clark was then plagued by questions about the remark, wasting valuable air time which could have been spent on shedding light on his campaign goals.
One strategist recently noted that were he advising the Republicans he would suggest buying Moore air time in the hope that his strident views would put many off the Democrat cause.
President Nixon appears to have been aware of the potential pitfalls of celebrity association when he insisted during a meeting with Elvis Presley - convened by the King himself - that they should they keep their rendez-vous private.
"Don't tell anybody. Preserve your credibility at all costs," he allegedly told the star at least three times, and the meeting did indeed remain a secret until a syndicated columnist broke the story 13 months later.
Elvis left the White House with a badge which confirmed his position as a "special assistant" of the Bureau of Narcotics and Dangerous Drugs, ecstatic that he had apparently obtained the president's ear.
Whether celebrities do indeed wield any influence on policy is a moot point; but the suggestion that they do is a dangerous one.
Bill Clinton, who had celebrity sleepovers at the White House, was attacked on a number of occasions for allegedly responding to stars' requests.
Actor and scientologist John Travolta, for instance, pressured Mr Clinton to condemn Germany for banning the religion among public employees, and Germany was indeed condemned in a human rights report issued by the US government in 1997.
The role of Mr Travolta's entreaties is, however, unclear.
Alan Schroeder does not believe celebrities do influence policy.
"But many stars do take themselves very seriously, and they like to look as if they have true depth. Whispering in the president's ear, even if it's to no effect, allows them to feel like that.
"That's what keeps these relationships alive."