Barack Obama has made a rare intervention in the 2020 White House race to decry a “despicable” racially charged attack ad against Joe Biden.
A pro-Trump group put out the clip that twists Mr Obama’s own words in order to undermine the Democratic contender.
Mr Biden is hoping the black vote in South Carolina’s primary on Saturday will revive his campaign.
Though Mr Biden was his vice-president, Mr Obama has observed neutrality in the race, refusing to endorse a contender.
Joe Biden is one of eight candidates remaining in the race to become the Democratic candidate who will take on President Donald Trump, a Republican, in November’s election,
What does the ad say?
The ad – entitled South Carolina, Joe Biden Can’t Be Trusted – was broadcast on TV stations in the southern state before Tuesday night’s Democratic debate in Charleston, formerly America’s largest slave port.
“Joe Biden promised to help our community,” says a female narrator in the video. “It was a lie.”
She introduces audio from Mr Obama in which he says: “Plantation politics. Black people in the worst jobs, the worst housing. Police brutality rampant.
“But when the so-called black committeemen came around election time, we’d all line up and vote the straight Democratic ticket.
“Sell our souls for a Christmas turkey.”
Captions flash up on screen attacking Mr Biden’s record on race, including his legislative co-operation in the 1970s with segregationist senators and his vote for a 1994 crime bill that many now blame for the mass incarceration of black people.
“Enough,” the female narrator cuts in. “Joe Biden won’t represent us, defend us or help us. Don’t believe Biden’s empty promises.”
How did Obama respond?
Mr Obama’s lawyers say they will file a cease-and-desist letter to immediately stop televisions stations in South Carolina running the clip.
“This despicable ad is straight out of the Republican disinformation playbook,” Katie Hill, Obama’s communications director, said in a statement.
“And it’s clearly designed to suppress turnout among minority voters in South Carolina by taking President Obama’s voice out of context and twisting his words to mislead viewers.
“In the interest of truth in advertising, we are calling on TV stations to take this ad down and stop playing into the hands of bad actors who seek to sow division and confusion among the electorate.”
Ms Hill reiterated that Mr Obama “has several friends in this race, including, of course, his own esteemed vice-president”.
But she added that he “has no plans to endorse in the primary because he believes that in order for Democrats to be successful this fall, voters must choose their nominee”.
Where is the ad from?
The ad uses excerpts from Mr Obama’s 1995 memoir, Dreams from My Father.
The former US president is heard in the audio reading a quotation from a Chicago barber expressing cynicism about the city’s Democratic politics.
The ad was put out by the Committee to Defend the President, which is devoted to re-electing Mr Trump.
The political action committee is run by a former Republican state legislator from Colorado, Ted Harvey.
Mr Harvey told Politico the ad is fair game, arguing that Mr Biden “is simply giving lip-service for votes”.
“That’s the point President Obama made in his book, and we have every right to use his own words – in his own voice – in the political forum,” he added.