Former Vice President Joe Biden Joe BidenFormer Pence aide: White House staffers discussed Trump refusing to leave office Progressive group buys domain name of Trump's No. 1 Supreme Court pick Bloomberg rolls out M ad buy to boost Biden in Florida MORE holds a 17-point lead in South Carolina’s presidential primary, according to a survey released Wednesday, with the Palmetto State again offering Biden his largest margin among the early-voting contests.

Thirty-three percent of likely South Carolina primary voters say they will support Biden in a new Monmouth University Poll survey, compared with 16 percent for Sen. Elizabeth Warren Elizabeth WarrenOvernight Defense: Appeals court revives House lawsuit against military funding for border wall | Dems push for limits on transferring military gear to police | Lawmakers ask for IG probe into Pentagon's use of COVID-19 funds On The Money: Half of states deplete funds for Trump's 0 unemployment expansion | EU appealing ruling in Apple tax case | House Democrats include more aid for airlines in coronavirus package Warren, Khanna request IG investigation into Pentagon's use of coronavirus funds MORE (D-Mass.) and 12 percent for Sen. Bernie Sanders Bernie SandersSirota reacts to report of harassment, doxing by Harris supporters Republicans not immune to the malady that hobbled Democrats The Hill's Morning Report - Sponsored by Facebook - Republicans lawmakers rebuke Trump on election MORE (I-Vt.). No other candidate breaks double digits in the poll.

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The poll marks a decline for Biden, who sat at 39 percent in Monmouth’s July poll, and an improvement for Warren, who rose 7 points since the summer. Sanders was at a similar 10 percent in July.

South Carolina will hold the 2020 cycle’s fourth nominating contest, after Iowa, New Hampshire and Nevada. According to the RealClearPolitics poll tracker, Biden leads surveys of South Carolina voters by an average of more than 20 percentage points, by far his largest margin in the early states.

The former vice president for months has banked on a deep well of support among black voters to help buoy his campaign, which has seen recent slides in the polls and has had to respond to verbal gaffes and uneasy debate performances. However, Biden’s numbers with African Americans appear to be slipping, with his position as either a first- or second-choice candidate falling by 10 points among black voters, down to 52 percent in Wednesday's poll.

Warren, who has leapfrogged Biden in several national and early state polls, appeared to benefit from that drop, as seen by a 15-point boost to her position as a top-two choice by black voters, up to 26 percent from 11 percent in July.

“Biden is still in a pretty good position in South Carolina, but there are some signs that he might not have a true firewall among black voters. If he does not do well in the earlier contests in February, there may be potential for current preferences to shift here,” said Patrick Murray, director of the independent Monmouth University Polling Institute.

Still, Biden maintains a double-digit lead among black primary voters, with 39 percent of such voters saying the former vice president is their top pick, compared with 11 percent for both Warren and Sanders.

Monmouth University's poll surveyed 402 likely South Carolina primary voters from Oct. 16-21 and has a margin of error of plus or minus 4.9 percentage points.