Sen. Bernie Sanders Bernie SandersKenosha will be a good bellwether in 2020 Biden's fiscal program: What is the likely market impact? McConnell accuses Democrats of sowing division by 'downplaying progress' on election security MORE (I-Vt.) is closing the gap between him and former Vice President Joe Biden Joe BidenSenate Republicans face tough decision on replacing Ginsburg What Senate Republicans have said about election-year Supreme Court vacancies Biden says Ginsburg successor should be picked by candidate who wins on Nov. 3 MORE when it comes to black voters, according to a new NBC News-Wall Street Journal national poll.

Among black Democratic primary voters surveyed, 31 percent said they back Biden, while 29 percent said they back Sanders, which fell well within the poll's margin of error.

The black voting bloc is a demographic that Biden has been able to point to as a strength during the Democratic nomination process.

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Aggregated data from 2019 versions of the NBC News-Wall Street Journal poll show that Biden's lead among black voters was as much as 30 percentage points at times last year.

Among black voters surveyed, just 14 percent said they approve of the job President Trump Donald John TrumpObama calls on Senate not to fill Ginsburg's vacancy until after election Planned Parenthood: 'The fate of our rights' depends on Ginsburg replacement Progressive group to spend M in ad campaign on Supreme Court vacancy MORE is doing in office, and the numbers show they would overwhelmingly choose any Democrat over the president in November.

Biden has struggled in the first two 2020 votes, finishing fourth in the Iowa caucuses and fifth in the New Hampshire primary. Sanders, meanwhile, has surged, virtually tying with former South Bend, Ind., Mayor Pete Buttigieg Pete ButtigiegBipartisan praise pours in after Ginsburg's death Bogeymen of the far left deserve a place in any Biden administration Overnight Defense: Woodward book causes new firestorm | Book says Trump lashed out at generals, told Woodward about secret weapons system | US withdrawing thousands of troops from Iraq MORE in Iowa and winning New Hampshire.

With only 139 respondents, the margin of error — plus or minus 8.31 percentage points — was high for this poll. NBC News admits that because of this, "it is difficult to differentiate the true levels of support for each of the candidates."