South Bend, Ind. Mayor Pete ButtigiegPete ButtigiegBiden hopes to pick VP by Aug. 1 It's as if a Trump operative infiltrated the Democratic primary process Here's how Biden can win over the minority vote and the Rust Belt MORE has slipped 4 percentage points in a new Hill-HarrisX poll of the Democratic presidential primary race that finds former Vice President Joe BidenJoe BidenDonald Trump and Joe Biden create different narratives for the election Poll: Biden widens lead over Trump to 10 points Biden: 'We are a nation in pain, but we must not allow this pain to destroy us' 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 BloombergMichael BloombergIt's as if a Trump operative infiltrated the Democratic primary process Liberals embrace super PACs they once shunned .7 billion expected to be spent in 2020 campaign despite coronavirus: report 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 SandersBernie SandersExpanding tax credit for businesses retaining workers gains bipartisan support The battle of two Cubas Coronavirus Report: The Hill's Steve Clemons interviews Rep. Ro Khanna MORE’s (I-Vt.) 19 percent.

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

Sanders and Elizabeth WarrenElizabeth WarrenThe Memo: Trump ratchets up Twitter turmoil Hillicon Valley: Twitter flags Trump tweet for 'glorifying violence' | Cruz calls for criminal investigation into Twitter over alleged sanctions violations | Senators urge FTC to investigate TikTok child privacy issues Warren condemns 'horrific' Trump tweet on Minneapolis protests, other senators chime in 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 CastroJulian CastroCastro, Warren, Harris to speak at Texas Democratic virtual convention Julián Castro to become senior advisor for Voto Latino It's as if a Trump operative infiltrated the Democratic primary process MORE has 4 percent support, while Sen. Amy KlobucharAmy KlobucharLiberal group asks Klobuchar to remove herself from VP consideration because of prosecutorial record Klobuchar on defense as Floyd death puts spotlight on record Officer involved in George Floyd death charged with third-degree murder and manslaughter MORE (D-Minn.), tech entrepreneur Andrew YangAndrew YangAndrew Yang discusses his universal basic income pilot program Andrew Yang on the George Floyd protests in Minneapolis McConnell challenger on how Yang endorsement could help him MORE and billionaire Tom SteyerTom SteyerBloomberg wages war on COVID-19, but will he abandon his war on coal? Overnight Energy: 600K clean energy jobs lost during pandemic, report finds | Democrats target diseases spread by wildlife | Energy Dept. to buy 1M barrels of oil Ocasio-Cortez, Schiff team up to boost youth voter turnout 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