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 in the crowded Democratic presidential primary as he fends off a growing challenge from 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.), according to a new Emerson College poll.

Biden gets the support of 25 percent of registered voters, a 6-point drop from the same poll in August. Meanwhile, Warren has surged to 23 percent support, an 8-point bump since last month’s survey. 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.) rounds out the top three with 22 percent, a 2-point fall from August.

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Entrepreneur Andrew Yang Andrew YangBiden's latest small business outreach is just ... awful Doctor who allegedly assaulted Evelyn Yang arrested on federal charges The Hill's Campaign Report: Biden weighs in on police shootings | Who's moderating the debates | Trump trails in post-convention polls MORE comes in at fourth place at 8 percent, beating out 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 with 6 percent and Sen. Kamala Harris Kamala HarrisTexas Democratic official urges Biden to visit state: 'I thought he had his own plane' The Hill's Campaign Report: Biden on Trump: 'He'll leave' l GOP laywers brush off Trump's election remarks l Obama's endorsements A game theorist's advice to President Trump on filling the Supreme Court seat MORE (D-Calif.) at 4 percent.

No other candidate polls higher than 2 percent.

The poll is one of several showing a tightening in the race among the top three candidates, while the rest of the 2020 contenders are relegated to the middle or bottom tiers. However, there is still hope for candidates hoping to improve their standing or overtake Biden — more than 52 percent of respondents said there is a chance they could change their minds.

Biden gets the support of 42 percent of voters aged 50 or older, while Sanders receives the support of 28 percent of voters under 50. Warren has 23 percent support from each group.

Among voters who backed Sanders’s insurgent 2016 primary against Hillary Clinton Hillary Diane Rodham ClintonBloomberg rolls out M ad buy to boost Biden in Florida Hillicon Valley: Productivity, fatigue, cybersecurity emerge as top concerns amid pandemic | Facebook critics launch alternative oversight board | Google to temporarily bar election ads after polls close Trump pledges to make Juneteenth a federal holiday, designate KKK a terrorist group in pitch to Black voters MORE, 37 percent still support him, while 23 percent back Warren, 10 percent support Biden and 9 percent back Yang.

Looking ahead to the general election, Warren and Biden are the Democratic contenders beating Trump, both by slim margins. Warren holds a 51-49 percent lead over the president, while Biden beats Trump by a 50-49 percent margin. Warren and Trump were tied in August’s poll, while Biden had an 8-point advantage last month.

The Emerson College poll surveyed 1,019 registered voters from Sept. 21 to Sept. 23 and has a margin of error of 3 percentage points.