Joe Biden's Support From Black Voters in South Carolina Has Declined 19 Percent Since Fall, New Poll Shows

Former Vice President Joe Biden has lost nearly one-fifth of his support among black voters in South Carolina, a new poll released Sunday finds.

Biden's overall support in the country's next primary state, which he has staked as his struggling campaign's turnaround, has fallen to just a single-digit lead over Vermont Senator Bernie Sanders versus his massive 28 percent lead over all candidates just three months ago. A CBS News/YouGov poll released Sunday also identifies another problem with Biden's potential wooing of black voters - Tom Steyer. The billionaire Democratic presidential candidate has skyrocketed from just 2 percent support among black South Carolina voters in November to 24 percent today.

And in that same time period, Biden has lost 19 percent of support, 54 to 35 percent, from black voters in South Carolina.

"I'm the only one who has the record and has the background and has the support" of the black electorate, Biden told Politico last week, echoing a claim he has made throughout his campaign. But the CBS News/YouGov data released over the weekend exposes a crack in his plan to draw overwhelming support from the majority-black primary voters on February 29.

Biden's 19-point fall among black voters has been coupled with his loss of white voters in South Carolina. In November, the same poll found Biden leading all other Democratic presidential candidates but now Sanders holds the lead among white voters. Additionally, analysts warn that Steyer's sharp rise in popularity among black voters could directly pull voters away from Biden next week.

But Biden may be set to receive a huge endorsement from House Majority Whip James Clyburn, who holds enormous influence in South Carolina. Clyburn is the highest-ranking African American in Congress and he announced on NBC Sunday, "I will endorse Wednesday morning. I'm going to tell everybody who I'm going to vote for. I'm just not going to do it today."

Meanwhile, black voters in South Carolina, according to the CBS News/YouGov poll, still say Biden understands the needs and issues affecting black voters "a lot" more than than any other Democratic candidate. This contrasts with data showing former South Bend, Indiana Mayor Pete Buttigieg continues to struggle among black voters nationwide, although he is currently in second in the overall delegate count behind frontrunner Sanders.

But Biden's campaign is expressing optimism that his candidacy will turn around in the Palmetto State on Saturday: "Nothing is certain until the big man says yes," a Biden advisor told Politico last week while discussing Clyburn's potential game-changing endorsement. "Clyburn is a kingmaker and he's going to do this his way."

Former Vice President Joe Biden greets supporters at a campaign rally at Teamsters Local 249 Union Hall April 29, in Pittsburgh. Biden on Monday voiced his support for allowing all Americans the option of buying into Medicare. Jeff Swensen/Getty Images