Former Vice President Joe Biden Joe BidenBiden on Trump's refusal to commit to peaceful transfer of power: 'What country are we in?' Democratic groups using Bloomberg money to launch M in Spanish language ads in Florida Harris faces pivotal moment with Supreme Court battle MORE leads a crowded field of potential 2020 Democrats, according to a new poll from CNN and SSRS.

One-third of Democrats and Democratic-leaning independents polled selected Biden as their choice to take on President Trump Donald John TrumpBiden on Trump's refusal to commit to peaceful transfer of power: 'What country are we in?' Romney: 'Unthinkable and unacceptable' to not commit to peaceful transition of power Two Louisville police officers shot amid Breonna Taylor grand jury protests MORE in 2020.

Other popular choices included Sen. Bernie Sanders Bernie SandersOutrage erupts over Breonna Taylor grand jury ruling Dimon: Wealth tax 'almost impossible to do' Grand jury charges no officers in Breonna Taylor death MORE (I-Vt.) with 13 percent and Sen. Kamala Harris Kamala HarrisHarris faces pivotal moment with Supreme Court battle Nearly 40 Democratic senators call for climate change questions in debates Joe Biden has long forgotten North Carolina: Today's visit is too late MORE (D-Calif.) at 9 percent.

Democratic Sens. Elizabeth Warren Elizabeth WarrenDimon: Wealth tax 'almost impossible to do' CNN's Don Lemon: 'Blow up the entire system' remark taken out of context Democrats shoot down talk of expanding Supreme Court MORE (Mass.) and Cory Booker Cory Anthony BookerBipartisan praise pours in after Ginsburg's death DHS opens probe into allegations at Georgia ICE facility Democratic lawmakers call for an investigation into allegations of medical neglect at Georgia ICE facility MORE (N.J.) were also possible candidates.

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Biden has consistently polled ahead of other Democrats and Trump in a number of surveys about potential 2020 showdowns.

But the former VP has not yet said whether he plans to run, saying last week that he is not running for president “at this point.”

The CNN poll also found that 46 percent of Americans say they think Trump will win reelection, a six-point increase from when the same question was asked in March. Another 47 percent think he will not win a second term.

The poll was conducted from October 4 to 7 among 1,009 adults. It has a margin of error of 3.8 percentage points.