Sen. Bernie Sanders Bernie SandersNYT editorial board remembers Ginsburg: She 'will forever have two legacies' Two GOP governors urge Republicans to hold off on Supreme Court nominee Sanders knocks McConnell: He's going against Ginsburg's 'dying wishes' MORE (I-Vt.) and former Vice President Joe Biden Joe BidenMomentum growing among Republicans for Supreme Court vote before Election Day Trump expects to nominate woman to replace Ginsburg next week Video of Lindsey Graham arguing against nominating a Supreme Court justice in an election year goes viral MORE are in a statistical dead heat atop the 2020 Democratic presidential field in Iowa just before the state’s caucuses, according to a poll released Sunday.

Sanders, at 26 percent, has a 1-point lead over Biden, which is within the margin of error of the CBS News poll, which was conducted by YouGov.

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Typically, 15 percent is the threshold for obtaining delegates in Iowa, but supporters can change their picks if their first choices do not reach the cutoff. Biden is expected to make gains from Klobuchar’s and others’ supporters, CBS News noted.

If Warren does not reach the level to obtain delegates, her supporters are likely to flock to Sanders's side, the network added.

More than a third of respondents say they have “definitely” made up their minds on their first-choice candidate, with 48 percent of Sanders’s voters and 40 percent of Biden’s committing to the candidates, respectively.

The poll was conducted between Jan. 16 and 23. A sample of 2,500 registered voters in Iowa were surveyed, including 1,041 self-identified Democrats and Democratic-leaning independents. The margin of error in the poll was 3.9 percent.