Former Vice President Joe Biden Joe BidenFormer Pence aide: White House staffers discussed Trump refusing to leave office Progressive group buys domain name of Trump's No. 1 Supreme Court pick Bloomberg rolls out M ad buy to boost Biden in Florida MORE holds a slim 2-point lead over his closest competitor in the Democratic primary field, according to a poll released Tuesday.

An Emerson poll conducted Oct. 18–21 found Biden in the lead with the support of 27 percent of Democratic primary voters, while Sen. Bernie Sanders Bernie SandersSirota reacts to report of harassment, doxing by Harris supporters Republicans not immune to the malady that hobbled Democrats The Hill's Morning Report - Sponsored by Facebook - Republicans lawmakers rebuke Trump on election MORE (I-Vt.) followed closely at 25 percent.

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Sen. Elizabeth Warren Elizabeth WarrenOvernight Defense: Appeals court revives House lawsuit against military funding for border wall | Dems push for limits on transferring military gear to police | Lawmakers ask for IG probe into Pentagon's use of COVID-19 funds On The Money: Half of states deplete funds for Trump's 0 unemployment expansion | EU appealing ruling in Apple tax case | House Democrats include more aid for airlines in coronavirus package Warren, Khanna request IG investigation into Pentagon's use of coronavirus funds MORE (D-Mass.), who previously led Sanders in the poll, slid 2 percentage points from the September poll and now sits in third place with 21 percent.

As with other recent polls, no other candidate besides the top three registered support in the double digits. South Bend, Ind., Mayor Pete Buttigieg Pete ButtigiegBillionaire who donated to Trump in 2016 donates to Biden The Hill's Morning Report - Sponsored by Facebook - GOP closes ranks to fill SCOTUS vacancy by November Buttigieg stands in as Pence for Harris's debate practice MORE (D) came in fourth place in October's poll with the support of just 6 percent of Democratic primary voters.

Sanders is strongest among younger voters, with 45 percent of the 18–29 age group supporting him, by far the largest of any Democratic candidate. Warren placed second among this group with 17 percent.

Biden had a similar level of support, 44 percent, among voters age 50 and over.

All three of the top-tier Democratic candidates in the poll led President Trump Donald John TrumpFederal prosecutor speaks out, says Barr 'has brought shame' on Justice Dept. Former Pence aide: White House staffers discussed Trump refusing to leave office Progressive group buys domain name of Trump's No. 1 Supreme Court pick MORE in hypothetical matchups by the same margin: 51 percent to 49 percent.

Emerson's poll, which contacted 430 registered Democratic primary voters and 1,000 voters overall, has a margin of error of plus or minus 4.7 percentage points among Democratic voters and 3 percentage points overall.