Democratic presidential hopefuls Vermont Senator Bernie Sanders (L) and former Vice President Joe Biden chat during a break in the fourth Democratic primary debate of the 2020 presidential campaign season co-hosted by The New York Times and CNN at Otterbein University in Westerville, Ohio on October 15, 2019.

Billionaire liberal activist Tom Steyer, who spent heavily in South Carolina in the early stages of the primary, lags behind the pair with 15% of support. Former South Bend, Indiana, Mayor Pete Buttigieg follows at 9%.

Biden gets 27% of support among likely Democratic voters in Saturday's presidential primary, while the Vermont senator garners 23%. The gap falls within the survey's plus-or-minus 6 percentage point margin of error.

Joe Biden and Bernie Sanders are locked in a tight South Carolina Democratic primary race as the former vice president tries to inject life into a struggling campaign, according to an NBC News/Marist poll released Monday.

Sens. Elizabeth Warren, D-Mass., and Amy Klobuchar, D-Minn., garner 8% and 5% of support, respectively. No other candidate tops 5%. Former New York Mayor Mike Bloomberg is not on the ballot in South Carolina.

The poll was conducted from Tuesday to Friday, meaning it was taken partly after the Nevada presidential debate but not after the results of Saturday's caucuses in the state. Sanders will win Nevada by a significant margin, while Biden and Buttigieg will come in distant second and third, respectively, according to NBC News.

Biden sees winning South Carolina as critical to reviving a flagging presidential campaign. After dismal showings in predominantly white Iowa and New Hampshire, the one-time front-runner argued his fortunes would improve once more diverse states had their say in the primary. As nominating contests started earlier this month, Biden led both Sanders and Steyer by more than 10 percentage points in a South Carolina polling average, according to RealClearPolitics.

In Saturday's Nevada caucuses, the first nominating contest where voters of color made up a major share of the electorate, Biden fared better. Still, he will finish in second place to Sanders with about 20% of county delegates in the state, according to NBC News.

"We're alive, and we're going to come back, and we're going to win," he told supporters Saturday.

Most polls throughout the primary have found black voters, who make up a majority of South Carolina's primary electorate, overwhelmingly favor Biden. But recent surveys indicate his support among black voters has waned.

Among black likely Democratic primary voters who responded to the NBC/Marist poll, Biden gets 35% of support. Sanders and Steyer follow at 20% and 19%, respectively.

A larger share of Steyer and Biden supporters said they might vote differently than Sanders backers. Among likely Democratic primary voters, 18% of those who picked Steyer said they might choose someone else, while 17% of Biden supporters said the same.

Only 7% of respondents who prefer Sanders said they might vote differently.