Joe Biden has taken a commanding lead in the crowded 2020 Democratic presidential nomination race, polling showed Tuesday, boosting the former vice president's standing as he began campaigning in early-voting Iowa.
The results of the CNN poll solidify frontrunner status for Biden, showing him breaking away from the pack of 20 candidates with 39 percent support among Democratic or Democratic-leaning voters. Liberal Senator Bernie Sanders was a distant second at 15 percent.
Progressive Senator Elizabeth Warren, young South Bend, Indiana Mayor Pete Buttigieg and former congressman Beto O'Rourke of Texas were bunched together with eight, seven, and six percent respectively.
But the survey also signaled that Americans are still a long way from making up their minds this far out from the statewide primaries, which kick off next February.
Only 36 percent of respondents with a preference said they will definitely back the candidate they currently support, while 64 percent said they could still change their minds. 
The poll of 1,007 respondents was conducted by SSRS research in the days after Biden officially joined the field last week, and shows his support surging by 11 percentage points since the previous survey, in March.
Biden, 76, officially joined the field last week and has hit the ground running. 
After a high-dollar fundraiser in Philadelphia, he took his campaign across Pennsylvania -- seen as critical for Democrats to regain the White House -- to address union workers in Pittsburgh on Monday.
Biden, who served as Barack Obama's vice president from 2009-2017 and describes himself as a "Biden-Obama Democrat," further aligned himself with his former boss in a new campaign video released Tuesday.
Obama has yet to weigh in on the 2020 Democratic field, and Biden was adamant that he personally asked Obama "not to endorse" him.
The video nevertheless features excerpts of the then-president's glowing speech when he presented Biden with the Medal of Freedom in 2017, in which he describes his deputy as "resilient, loyal, and a patriot."
The opening salvos of Biden's campaign have centered on directly taking on Donald Trump as he makes the case that the current president is a "threat" to America and lacks the moral decency to serve the nation.
"If I'm going to be able to beat Donald Trump in 2020 it's going to happen here," he told the crowd in Pittsburgh, a blue-collar city remaking itself as a tech hub.
In an interview that aired Tuesday on ABC, Biden said he seeks to "end this god-awful deliberate division" being created by Trump.
Biden traveled Tuesday to Iowa, which votes first in the party nomination process, for a two-day debut campaign swing through the state.
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