Biden maintains 19-point lead over Sanders in new poll

Former vice president Joe BidenJoe BidenTrump hits Fox News's Chris Wallace over Ukraine coverage Schiff: Whistleblower testimony might not be necessary Trump warns Democrats will lose House seats over impeachment MORE leads Sen. Bernie SandersBernie SandersSanders wishes Ocasio-Cortez happy birthday Video of fake Trump shooting members of media shown at his Miami resort: report Sanders can gain ground by zeroing in on corruption MORE in the latest Hill-HarrisX poll released Monday by 19 points, maintaining a clear separation from the rest of the field in the Democratic presidential primary,

Biden won 35 percent support from Democratic and Democratic-leaning independent registered voters in the June 1-2 survey, compared to 16 percent for Sanders (I-Vt.).

South Bend, Ind. Mayor Pete ButtigiegPeter (Pete) Paul ButtigiegTrump hits Fox News's Chris Wallace over Ukraine coverage Sanders can gain ground by zeroing in on corruption Biden praises Buttigieg for criticizing GOP attacks: 'That's a good man' MORE was a distant third with 8 percent. He was followed by Sen. Elizabeth WarrenElizabeth Ann WarrenSanders can gain ground by zeroing in on corruption Biden praises Buttigieg for criticizing GOP attacks: 'That's a good man' Warren enters crucial debate with big momentum MORE (D-Mass) at 5 percent.

Sen. Kamala HarrisKamala Devi HarrisRepublicans wrestle with impeachment strategy Klobuchar takes shots at health and education plans supported by Sanders and Warren Kamala Harris to Trump Jr.: 'You wouldn't know a joke if one raised you' MORE (D-Calif.) and former Rep. Beto O'RourkeBeto O'RourkeButtigieg pushes back on O'Rourke threat to strip religious institutions of tax-exempt status O'Rourke raises .5 million in third quarter Conservatives slam Beto O'Rourke over threat to tax-exempt status for religious organizations MORE were supported by 4 percent of respondents while Sen. Cory BookerCory Anthony BookerRepublicans wrestle with impeachment strategy O'Rourke campaign says path to victory hinges on top 5 finishes in Iowa, Nevada O'Rourke raises .5 million in third quarter MORE (D-N.J.) was named by 3 percent.

All of the other Democratic candidates were named by 1 percent or fewer survey participants. Seventeen percent of respondents said they were unsure about their preference.

The results overall are largely similar to a May 17-18 Hill-HarrisX survey which also found Biden with a 19 percent lead over his Vermont-based rival. The former vice president received 33 percent support in the earlier poll while Sanders received 14 percent.

The May survey showed Warren in third place with 8 percent support and Buttigieg in fourth with 6 percent. The shift between the two candidates' support within the polls is within the surveys' sampling margins of error.

The newer poll found Biden as the top named candidate of both men and women and also across all age groups, although his lead over Sanders among voters between 18 and 34 was just one point, indicating a statistical tie. Older voters were overwhelmingly more likely to prefer the former vice president to other candidates with 47 percent of respondents 50 years old and older supporting him.

Among white voters, Biden was the preferred candidate while Sanders and Buttigieg were essentially tied for second-place. Biden enjoyed an even stronger lead among black respondents while Sanders showed strength among Hispanics although the sample size for both groups is too small to state this definitively.

Since Biden's entry into the presidential contest in April, the race has become relatively stable with no candidate able to dislodge Sanders from second-place and Biden from first, although that may change following the first debate contest which will be hosted by the Democratic National Committee June 26 and 27.

Presidential aspirants sharpened their messages over the weekend at the California Democratic Party's annual convention in San Francisco where several candidates called for impeaching President TrumpDonald John TrumpWHCA calls on Trump to denounce video depicting him shooting media outlets Video of fake Trump shooting members of media shown at his Miami resort: report Trump hits Fox News's Chris Wallace over Ukraine coverage MORE. Former Colorado Gov. John HickenlooperJohn HickenlooperGardner dodges questions about Trump's call for Biden probe 2020 Presidential Candidates Krystal Ball: Yang campaign a 'triumph of substance over the theatre' MORE was booed by attendees after he expressed skepticism about a proposed Green New Deal environmental initiative and proposals to have the federal government administer medical insurance for all Americans.

Warren and Buttigieg took veiled swipes at Biden at the event with the Massachusetts senator implicitly denouncing his recent declarations that Republicans would become more inclined toward bipartisanship if President Trump is defeated in 2020. Buttigieg said that Democrats needed "a new generation of leaders," a reference to Biden's age of 76 years.

Sanders indirectly slammed Biden for skipping the event and argued that the party would not be able to defeat Trump unless it embraced a progressive agenda.

The latest Hill-HarrisX survey was conducted June 1-2 among a statistically representative sample of 1,001 registered voters. The question about 2020 Democratic presidential preference was asked of a subset of 431 respondents who said they were Democrats or independents who leaned toward the Democratic Party.

The larger survey has a 3.1 percent sampling margin of error and a 95 percent confidence level. The subset has a sampling margin of error of 4.7 percentage points.

—Matthew Sheffield