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.) leads his Democratic presidential rivals by double digits in a new poll released just days before the next nominating contest in Nevada.

Sanders holds a 12-point lead over his nearest rivals in the NBC News/Wall Street Journal poll released Tuesday.

The poll shows Sanders at 27 percent support, followed by 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 at 15 percent and former New York City Mayor Mike Bloomberg and Sen. Elizabeth Warren Elizabeth WarrenBiden's fiscal program: What is the likely market impact? Warren, Schumer introduce plan for next president to cancel ,000 in student debt The Hill's 12:30 Report - Presented by Facebook - Don't expect a government check anytime soon MORE (D-Mass.) tied at 14 percent.

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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 (D) and Sen. Amy Klobuchar Amy KlobucharThe Hill's Morning Report - Sponsored by The Air Line Pilots Association - White House moves closer to Pelosi on virus relief bill EPA delivers win for ethanol industry angered by waivers to refiners It's time for newspapers to stop endorsing presidential candidates MORE (D-Minn.) round out the top six candidates, with 13 percent and 7 percent, respectively.

“There is one clear and inescapable set of results: Bernie Sanders is the definitive [Democratic] front-runner, and the current numbers do not represent his ceiling, but instead his base with room to grow,” Democratic pollster Peter Hart, who conducted the survey with GOP pollster Bill McInturff of Public Opinion Strategies, told NBC News.

“His downsides are there,” Hart said, “but they’ve yet to be exploited by his opponents.”

While Sanders had similar numbers in a January version of the same poll, Biden lost more than 10 points since last month, when he pulled 26 percent. Meanwhile, Bloomberg and Buttigieg are up 5 points and 6 points, respectively, while Warren is down 1 point.

The poll finds that Biden has lost ground with African American voters specifically, a key voter demographic in South Carolina, which holds its primaries Feb. 29. Biden's numbers among that group nationally have fallen from 52 percent in January to 38 percent this month, while Bloomberg has reached 18 percent among those voters.

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In a head-to-head matchup between Sanders and Bloomberg, Sanders leads by 20 points — 57 percent to 38 percent support — and he leads against Buttigieg by nearly as much, 54 percent to 38 percent, according to the poll.

The survey follows an NPR poll released earlier Tuesday that also found Sanders holding a 12-point lead in the race. That survey showed him leading the field with 31 percent support, while it showed Bloomberg in second place with 19 percent support.

The NBC/Wall Street Journal poll of 426 Democratic primary voters was conducted Feb. 14-17 and has a 4.75-point margin of error.