Sen. Amy Klobuchar Amy KlobucharSocial media platforms put muscle into National Voter Registration Day Battle lines drawn on precedent in Supreme Court fight Sunday shows - Ruth Bader Ginsburg's death dominates MORE (D-Minn.) has moved up in an Iowa poll of potential 2020 Democratic presidential candidates, coming in as the fourth most-popular contender with the support of 10 percent of respondents, according to a Focus on Rural America poll first obtained by Politico.

Klobuchar came in after former Vice President Joe Biden Joe BidenBiden on Trump's refusal to commit to peaceful transfer of power: 'What country are we in?' Democratic groups using Bloomberg money to launch M in Spanish language ads in Florida Harris faces pivotal moment with Supreme Court battle MORE, who received 30 percent; Sen. Bernie Sanders Bernie SandersOutrage erupts over Breonna Taylor grand jury ruling Dimon: Wealth tax 'almost impossible to do' Grand jury charges no officers in Breonna Taylor death MORE (I-Vt.), who received 13 percent; and former Senate candidate Rep. Beto O'Rourke Beto O'RourkeJimmy Carter says his son smoked pot with Willie Nelson on White House roof O'Rourke endorses Kennedy for Senate: 'A champion for the values we're most proud of' 2020 Democrats do convention Zoom call MORE (D-Texas), who received 11 percent.

O'Rourke and Klobuchar were new entries to the Focus on Rural America poll, which circulated without their names in September.

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The poll found that Biden's support dropped, from 37 percent in September to 30 percent in December.

The poll surveyed Iowa voters likely to attend the Democratic presidential caucus in 2020.

Sen. Elizabeth Warren Elizabeth WarrenDimon: Wealth tax 'almost impossible to do' CNN's Don Lemon: 'Blow up the entire system' remark taken out of context Democrats shoot down talk of expanding Supreme Court MORE (D-Mass.) took a significant hit, dropping from 16 percent support in September to 9 percent in December.

The other potential candidates to receive more than 2 to 3 percent were Sen. Kamala Harris Kamala HarrisHarris faces pivotal moment with Supreme Court battle Nearly 40 Democratic senators call for climate change questions in debates Joe Biden has long forgotten North Carolina: Today's visit is too late MORE (D-Calif.), with 7 percent support, and Sen. Cory Booker Cory Anthony BookerBipartisan praise pours in after Ginsburg's death DHS opens probe into allegations at Georgia ICE facility Democratic lawmakers call for an investigation into allegations of medical neglect at Georgia ICE facility MORE (D-N.J.), with 6 percent.

Majorities of Iowa caucus-goers said they are seeking a candidate who will take the lead in the fight against climate change (90 percent), heal divisions in the U.S. (87 percent), and address the "high cost of living" (85 percent).

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Only 30 percent of those surveyed who said they caucused for Sanders in 2016 said they will stay with him in 2020. A majority say they are interested in campaigning for other Democratic candidates.

Klobuchar and Biden found the most support from those who caucused for former Democratic presidential nominee Hillary Clinton Hillary Diane Rodham ClintonDemocratic groups using Bloomberg money to launch M in Spanish language ads in Florida The Hill's Campaign Report: Presidential polls tighten weeks out from Election Day More than 50 Latino faith leaders endorse Biden MORE in 2016.

The Focus on Rural America poll surveyed 500 registered voters in Iowa who said they were likely to participate in the Democratic presidential caucus in 2020. The interviews were conducted between Dec. 10-11 with a margin of error of plus or minus 4.4 percentage points.