In the black community it's known as trash-talking.
Ever since he loped on to the political stage in Chicago nearly 20 years ago, Barack Obama has had to contend with the jealousy of prominent black politicians. The Reverend Jesse Jackson seethed with resentment at the effortless way the younger man snatched the spotlight away from an earlier generation of black leaders whose roots lay in the civil rights movement.
In the gritty world of Chicago's south side, the mixed-race Mr Obama soon found himself being called "a mercenary for white elites" by some of his political rivals. As recently as last year, Mr Jackson complained in public that Mr Obama was "acting like he's white" for failing to make a stink when six black schoolboys were put on murder charges in Jena, Louisiana, after a melée with white pupils.
Now Mr Jackson has been caught speaking crudely about Mr Obama into a microphone, which he apparently thought was not live. It was just the latest in a long line of public slap-downs by the man who still views himself as America's pre-eminent black leader. For almost eight years the firebrand pastor turned politician has been trying to put Mr Obama in his place, while (usually) saying nice things about him in public.
Before a television interview this week, Mr Jackson complained sotto voce to a visibly astonished Fox News anchorman that Mr Obama was "talking down to black people", particularly black men, when he had complained in speeches that they were not behaving responsibly as fathers. He went on to express a desire to do something so crude to Mr Obama's anatomy that most American newspapers have decided not to print it. Even Fox News decided to wait three days before airing the offensive words (he wanted to "cut his [Barack Obama's] nuts out") allowing Mr Jackson plenty of time to apologise profusely for something most viewers knew nothing about.
"I don't want harm nor hurt to come to this campaign," Mr Jackson gushed after Fox News said they would be airing the recording of his comments, which he called "hurtful and wrong", on Wednesday night.
Mr Jackson, who ran for the White House in 1984 and in 1988, supports Mr Obama's White House bid – at least in public. But every now and then the tensions between the two men burst into the open. The former pastor sees himself as a crusader for the hidden, impoverished America and standard bearer for Martin Luther King. He cradled the civil rights leader in his arms after he was shot by an assassin and appeared on television still wearing a shirt stained with Mr King's blood.
Barack Obama himself acknowledges that it was Mr Jackson who inspired him to believe that a black man could win the White House, after he saw him speak in a debate at New York's Columbia University in 1984. But while he admired the older man's showmanship, he also realised that to win the confidence of Middle America, a successful black candidate would have to appear, and speak in a way that transcends race and the angry politics of the ghetto.
Instead of pushing himself to the head of civil rights marches, Mr Obama chose to operate behind the scenes as a community organiser, trying to get poor black people to unite and become powerful in demanding changes in their lives. Mr Obama's political mentor was Chicago's first black mayor, Harold Washington, rather than Jesse Jackson, who at the time was strutting on the national stage.
Mr Jackson's first run for the Democratic nomination ended in failure, but it was the most successful campaign by a black candidate until that time. He has a gift for oratory and a wicked turn of phrase, such as "Our time has come", "If your mind can conceive it and your heart can believe it, then you can achieve it".
But Mr Jackson caused howls of outrage when he described New York City as "Hymietown" in 1984. Again, he thought he was speaking privately to a black journalist, but his anti-Semitic remarks were splashed across the newspapers costing him valuable support among Jewish voters who were instinctively sympathetic to his cause of lifting up impoverished black communities.
The rivalry is understandable since Mr Obama and Mr Jackson are both products of America's most racially divided city, from which both emerged as champions of the poor to seek the highest office in the land.
There are overlapping family ties as well. Mr Obama's marriage in 1992 brought the families close. Michelle Obama was at high school with Mr Jackson's oldest child, Santita, and they were close friends. Santita sang at the Obamas' wedding and was godmother to their oldest daughter, Malia. Mrs Obama was a frequent visitor to Mr Jackson's Chicago home and as soon Mr Obama began dating her, he got to meet Jesse Jackson Jnr, who would also attend their wedding.
The self-regarding former pastor has a habit of rubbing Barack Obama up the wrong way. Spying Mr Obama's youngest daughter, Sasha, at an event, he lifted her up and put her on a pedestal to pose for pictures. Then when the cameras had stopped flashing, Mr Jackson walked away, leaving the three-year-old girl teetering on a tall block of concrete.
Eight years ago when Mr Obama was a little-known state senator in Illinois, he decided to mount an audacious challenge against Bobby Rush, a four-term US senator and former Black Panther. He immediately ran into some formidable opposition in the shape of Jesse Jackson and the former president Bill Clinton, who took steps to put the young upstart in his place. Mr Clinton overrode his own policy of staying out of Democratic primaries and backed Mr Rush, who trounced Mr Obama by more than two to one.
There were other times when Jesse Jackson tried to body block the Mr Obama's rise. Back in 1995, he even tried to arrange for his son to get the state senate seat that became Mr Obama's stepping stone to national fame. Mr Jackson's son, rejected the plan and ran successfully ran for Congress instead.
The younger Jackson, who is 42, is now a close friend to Mr Obama, 46, and is a national co-chairman of the Obama campaign. It is not the first time that congressman Jesse Jackson Jnr has found himself rebuking his father. After the Fox News episode, he said: "I'm deeply outraged and disappointed in Reverend Jackson's reckless statements about Senator Barack Obama," adding that the remarks were "divisive and demeaning ... Reverend Jackson is my dad and I'll always love him. [But] I thoroughly reject and repudiate his ugly rhetoric. He should keep hope alive and any personal attacks and insults to himself."
When the Chicago congressman's father wrote a newspaper column questioning Mr Obama's commitment to the needs of black voters, he penned a response in The Chicago Sun-Times under the headline "You're wrong on Obama, Dad".
Mr Obama has graciously accepted Mr Jackson's apology and the controversy seems destined to blow over. More than that, it could even help Mr Obama win back support he lost from white working-class voters in the primary contest with Hillary Clinton. And criticism from Jesse Jackson seems most unlikely to undercut Mr Obama's strong support among black voters, while the very public row with the maverick of racially tinged, left-wing urban politics can only reinforce Mr Obama's message to Middle America that he is a totally new kind of black politician.
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