(CNN) Former Vice President Joe Biden and Sen. Bernie Sanders of Vermont top the Democratic presidential candidates in South Carolina, according to a new poll from NBC/Marist released Monday.

The poll was conducted in its entirety before Sanders won the Nevada caucuses on Saturday.

The Monday poll release marks the third survey out of South Carolina in recent days with Biden and Sanders within the margin of error of each other, showing that the state -- which was once led by Biden -- is now a more competitive race.

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