Iowa voters appear split on the 2020 Democratic presidential primary, according to a new poll that places four candidates within the margin of error for the top spot in the field.

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 and 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.) are leading the primary field in the first-in-the country caucus state with 22 percent support each, according to a CBS News-YouGov poll released Sunday.

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 closely trails at 21 percent, and 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’s (D-Mass.) 18 percent also falls within the 4.1 percent margin of error, placing the four candidates in a statistical dead heat for the top spot in Iowa.

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No other candidate registered double-digit support, with Sens. 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.) and Amy Klobuchar Amy Klobuchar3 reasons why Biden is misreading the politics of court packing Social media platforms put muscle into National Voter Registration Day Battle lines drawn on precedent in Supreme Court fight MORE (D-Minn.) tied in a distant fifth place with 5 percent each.

Buttigieg has seen a 15-point uptick since a CBS-YouGov poll of Iowa voters in September that placed him at 6 percent support.

Sanders’s support has increased 3 points since September, while Warren has seen a 10-point dip and Biden’s support has decreased 3 points in Iowa.

Buttigieg saw a similar surge in a CNN poll released Saturday that placed him at him at 25 percent support, leading Sanders and Biden by 10 points and Warren by 9 points.

The new CBS-YouGov poll surveyed 856 registered Democratic voters and was conducted between Nov. 6 and Nov. 13.