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 has slipped 4 percentage points in a new Hill-HarrisX poll of the Democratic presidential primary race that finds former Vice President Joe Biden Joe BidenBiden says voters should choose who nominates Supreme Court justice Trump, Biden will not shake hands at first debate due to COVID-19 Joe Biden should enact critical government reforms if he wins MORE still leading the pack.

The nationwide survey published Wednesday found that Buttigieg dropped from 9 percent support to 5 percent among likely Democratic voters and Democratic-leaning independents. The South Bend mayor is now in a dead heat for fourth place with former New York Mayor Michael Bloomberg Michael BloombergBloomberg rolls out M ad buy to boost Biden in Florida Democratic groups using Bloomberg money to launch M in Spanish language ads in Florida Bloomberg pays fines for 32,000 felons in Florida so they can vote MORE, who also received 5 percent support.

Buttigieg had recently worked his way to the front of the 2020 Democratic primary, particularly in early primary and caucus states Iowa and New Hampshire. According to the RealClearPolitics averages, Buttigieg leads with 22.4 percent support in Iowa and holds second place in New Hampshire with 17.7 percent support, behind Sen. Bernie Sanders Bernie SandersTrump, Biden will not shake hands at first debate due to COVID-19 Sanders tells Maher 'there will be a number of plans' to remove Trump if he loses Sirota reacts to report of harassment, doxing by Harris supporters MORE’s (I-Vt.) 19 percent.

Biden, meanwhile, continues to top the Hill-HarrisX survey at 29 percent.

Sanders and 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.) followed, each receiving 13 percent support as they jockey to claim the mantle of the party's progressive wing.

Former Housing and Urban Development Secretary Julian Castro Julian CastroSanders says Democrats should have given more speaking time to progressives Castro says DNC should have put more Latino speakers on stage from beginning Jill Biden defends husband's cognitive ability from Trump attacks: 'It's ridiculous' MORE has 4 percent support, 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.), tech 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 and billionaire 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 each garnered 3 percent. The rest of the Democratic field registered at 2 percent or less.

The survey comes ahead of Thursday’s 2020 primary debate in Los Angeles, where seven candidates are poised to take the stage.

The sixth Democratic debate has been threatened by two separate labor disputes.

The event was initially supposed to be held at the University of California-Los Angeles but was moved after a local labor group accused the university of “illegal practices” and announced that it was boycotting campus speakers.

The debate’s new location at Loyola Marymount University has also faced a boycott over a fight with a union representing university workers. All seven of the Democrats who qualified for the debate at first threatened to skip the event due to the conflict, but the union has since announced an agreement with food services company Sodexo, allowing for it to continue as planned.

The Hill-HarrisX poll was conducted among 456 likely Democratic voters and Democratic-leaning independents between Dec. 13 and 14. It has a margin of error of 4.6 percent points.

—Tess Bonn