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. 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.) lead a new poll of likely Iowa caucusgoers by a wide margin as Sens. 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.) and 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.) fade.

The poll was conducted for Focus on Rural America, a Democratic group run by former Iowa Lt. Gov. Patty Judge (D) and Iowa political strategist Jeff Link. It found Biden on top among likely caucusgoers with 25 percent of the vote, virtually tied with Warren, who took 23 percent.

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) clocks in with 12 percent of the vote, finishing ahead of Sanders and Harris.

Sanders took 9 percent, while Sen. 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.), who is trying to make a charge in the neighboring state, took 8 percent.

ADVERTISEMENT

Harris took 5 percent, while billionaire former hedge fund manager Tom Steyer Tom SteyerTV ads favored Biden 2-1 in past month Inslee calls Biden climate plan 'perfect for the moment' OVERNIGHT ENERGY: Trump administration finalizes plan to open up Alaska wildlife refuge to drilling | California finalizes fuel efficiency deal with five automakers, undercutting Trump | Democrats use vulnerable GOP senators to get rare win on environment MORE clocked in at 3 percent. Sen. Cory Booker Cory Anthony BookerThe movement to reform animal agriculture has reached a tipping point Watchdog confirms State Dept. canceled award for journalist who criticized Trump 3 reasons why Biden is misreading the politics of court packing MORE (D-N.J.) and 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 each took 2 percent, and five candidates took 1 percent of the vote among the 500 voters surveyed.

The trend lines look good for Warren, who has grown her support in the last two Focus on Rural America polls, and Biden, who has remained steady since the group's March 2019 poll. Buttigieg has seen his support increase in all three surveys in which his name has been included.

Sanders and Harris have seen their support plummet. In the group's March poll, Sanders had backing from 17 percent of Iowa caucusgoers, making him Biden's chief rival. Harris, meanwhile, surged to 18 percent in the group's July poll, just after her strong performance in the first Democratic debates. Both have since slumped.

More voters see Warren in a positive light, 84 percent, than any other Democratic candidate. Buttigieg is seen positively by 81 percent, Biden by 76 percent and Booker by 75 percent. More voters say they are actively considering Warren, 70 percent, than any other potential candidate, suggesting she has room to grow.

Lesser-known candidates like Yang and Montana Gov. Steve Bullock Steve BullockCourt removes Pendley from role as public lands chief On The Trail: Making sense of this week's polling tsunami McConnell locks down key GOP votes in Supreme Court fight MORE (D) have seen their positive ratings spike the most in the months since the group's last poll, while Harris and former Housing and Urban Development Secretary Julián Castro have seen their positive ratings fall most dramatically.

The percentage of voters who have a negative opinion of Castro has doubled, from 14 percent in July to 29 percent now, days after Castro attacked Biden at the most recent Democratic debate. Six in 10 likely caucusgoers said they had ruled out Castro as a potential candidate, more than anyone except Yang. Eighteen percent of likely caucusgoers said they had ruled Castro out as a possibility based solely on his debate performance.

Focus on Rural America has been pushing Democratic candidates to campaign beyond Des Moines, Iowa City and Sioux City. Judge has toured ethanol plants with several candidates in hopes of getting them into rural settings.

"If Democrats keep showing up in rural communities and standing up for rural voters, we will win the 2020 election," Judge said in a statement.

The poll, conducted Sept. 14–17 — entirely after the third round of Democratic debates — surveyed 500 likely caucusgoers by cellphone and landline. Conducted by David Binder Research, the same pollster who surveys for Harris's campaign, the poll carried a margin of error of plus or minus 4.4 percentage points.