Jesse Jackson feels the heat as political rival steals his thunder, and mistress

But the man who inspired the ruthless New York preacher in Tom Wolfe’s Bonfire of the Vanities has also been the cause of a few sleepless nights for the Rev Jesse Jackson, the man he would like to replace as America’s favourite black politician.

As he eyes up the Democratic nomination for the White House in 2004, Mr Sharpton has stolen his rival’s thunder, pilfered his political power base and now, in his most audacious move so far, he’s waltzed off with his rival’s old mistress.

Mr Sharpton, the man once branded the "Beast of the Bronx", seized the opportunity to get one over on Mr Jackson at the private party for the opening of his National Action Network’s West Coast office.

The gamble paid off. Not only did Karin Stanford - Mr Jackson’s former mistress and the mother of his two-year-old love child, Ashley - accept Mr Sharpton’s invitation to join him at the private party, she also took a swipe at her old flame by telling guests: "Sharpton is the only civil rights leader I respect and support."

The story was gleefully reported in the New York Post’s Page Six gossip column yesterday, with the paper quoting one guest at the Los Angeles party as saying: "She made her presence known."

The paper also reported a source close to Mr Jackson who remarked that it was the first time Ms Stanford had broken ranks with her former lover: "She’s been straight-up with him through the whole thing ."

Mr Sharpton’s coup may have captivated the gossip columnists but it is just the latest flashpoint in what the New York Post dubbed the "War Between the Revs".

When Mr Jackson recently announced that he would be seeking the presidency in 2004, Mr Sharpton did not miss the opportunity to have a dig at his rival. "I do feel it’s time that I share the stage with Jackson as an equal," he said.

In a hard-hitting interview earlier this year, he began to land his blows beneath the belt, demanding: "Did I take the blood of the guy I love and put it on my shirt?" It was a clear reference to claims that when Martin Luther King was assassinated in 1968, Mr Jackson dipped his hand in the blood and smeared it on his own shirt, which he then wore to appear on national television the next morning.

For Mr Jackson, however, it was not the words of his rival which dealt the body blow to his political ambitions, but a disaster of his own making.

His affair with Ms Stanford began in the summer of 1999 and the child was conceived in August that year. When she was four months pregnant, she accompanied Mr Jackson to the White House to meet President Bill Clinton, who had received public support and counselling from Mr Jackson when his own affair with Monica Lewinsky was exposed.

When the child was born, Ms Stanford left the father’s name on the birth certificate blank. Mr Jackson abandoned his bid for the 2000 Democratic presidential nomination to try to prevent details of the liaison with Ms Stanford, who ran the Washington office of his Rainbow-PUSH coalition, leaking out during the campaign.

Despite their caution, the affair was eventually exposed last January. Mr Jackson declared himself "truly sorry for my actions" and urged the American public to show forgiveness: "If there are any among us who have not known the trials and tribulations and temptations, then throw a rock," he said. "Sex is not the one string on the guitar. There are nine more Commandments."

Matters worsened when it emerged that Ms Stanford had moved to California and had been paid 28,000 by a charitable fund connected with Operation Push, and the couple’s protracted negotiations over a financial settlement ended talk of marriage.