“When we rallied together to defend our president and all the progress he made they had his back,” the narrator says. Panning to then-Vice President Biden, the voice-over continues, “He had his back,” and moving to images of African American supporters at an Obama rally, says: “And you had his back.”

The ad then shifts to a black-and-white image of Sanders.

“But back in Washington, there was one guy with another plan,” the narrator says before an audio clip is heard of Sanders saying, “I think it would be a good idea if President Obama faced some primary opposition.”

The ad is part of a broader $600,000 digital buy in South Carolina that the campaign is considering spinning into a broadcast ad.

“Bernie Sanders was seriously thinking about challenging our first African American president in a primary,” the narrator says, citing an Atlantic report titled: “The Hidden History of Sanders’s Plot to Primary Obama.”

The Sanders campaign denies that Sanders ever had designs about mounting a primary campaign against Obama.

“This never happened. Bernie Sanders never considered a primary challenge to Obama,” deputy campaign manager Ari Rabin-Havt said in a statement. “Bernie was running for reelection in 2012, and that’s what he was focused on.”

Biden is attempting to shore up his own strength with African Americans, who on Saturday will play an outsize role for the first time in the 2020 primary cycle. In the meantime, Buttigieg is trying to make inroads with black voters in South Carolina — an electorate with which he's so far had little success — as he attempts to remain viable going into Super Tuesday.



And Bloomberg, who will not appear on a ballot in South Carolina, is attempting to slow Sanders' surge as the billionaire businessman is poised to face his first test in Super Tuesday states.

Bloomberg unleashed his own 90-second video spot saying Sanders was elected to the House in 1990 with the support of the National Rifle Association.

Ominous music plays in the background and subtitles read: “Bernie voted with the NRA and opposed federal background checks.”

The ad cited Sanders' opposition to a background check bill in the 1990s and votes in the early 2000s against allowing lawsuits against gun manufacturers, issues that aligned with the NRA’s stance.

“The NRA never endorsed Bernie Sanders and he has never taken a dime of their money. In fact, he lost his 1988 congressional race because he backed an assault weapons ban," Sanders senior adviser Jeff Weaver said. “But even after that, Sanders maintained his opposition to these weapons of war.”