The Quinnipiac University poll published on Tuesday found that Biden is leading the pack at 32 percent, followed by Senators Elizabeth Warren (D-Mass.) at 21 and Bernie Sanders (I-Vt.) at 14.
Among Democratic and Democratic-leaning voters, Warren’s support showed a 5-percent rise compared to last month. Sanders also saw a bump of 3 percentage points.
The survey also found that Senator Kamala Harris (D-Calif.), who peaked at 20 percent support in early July after the June Democratic debates, continued a downward trend and dipped to 7 percent.
Pete Buttigieg, the young mayor of South Bend, Indiana, placed fifth in the poll with 5 percent support.
The Quinnipiac poll, conducted by telephone, surveyed 807 Democratic and Democratic-leaning voters between August 1 and 5 with a margin of error of 4.1 percentage points.
The poll comes less than a week after the second round of Democratic primary debates in Detroit, Michigan, where Biden was savaged over his role in the implementation of controversial immigration policies in the administration of former President Barack Obama.
Since launching his bid for 2020 presidency, the veteran politician has been referred to as “Sleepy Joe” by US President Donald Trump, among other cases of name-calling.
Separately on Tuesday, the 76-year-old Democratic front-runner rebuked Trump’s rhetoric on race and religion after the deadly mass shootings at the weekend, saying it was not representative of the US.
“This fomenting hate, this talk about how in fact there are good people and a whole — and pitting us against one another based on our race, our religion, our ethnic background. That’s not America. It’s not who we are,” Biden said.
“Well, let me tell you, Sleepy Joe is going to wake him up really quickly because none of this changes as long as he’s president of the United States of America,” he added.
Multiple shootings in El Paso, Texas, and Dayton, Ohio, claimed 31 lives in less than a day over the weekend.
While Trump has called for his country to “condemn bigotry, hatred and white supremacy,” his critics say some of the blame for a rise in hate-driven violence lies with him.