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 and 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 lead the field of potential Democratic presidential nominees in 2020, a Public Policy Polling (PPP) survey released Tuesday shows.

When Democratic voters are asked to pick from a field of nine Democratic candidates, 31 percent pick the vice president and 24 percent favor the Vermont senator to be the Democratic nominee.

On the other hand, the PPP survey also found that Democratic voters want a younger candidate who hasn't run for president before. Sanders and Biden are both in their 70s and have run for the White House before.

Another 16 percent of poll respondents said they would vote for Sen. 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 (D-Mass.) if she ran, while 14 percent were undecided.

Other candidates mentioned have low support.

Only 4 percent of those surveyed said they would vote for New Jersey Sen. Cory Booker, while 2 percent each said they would pick Ohio Sen. Sherrod Brown Sherrod Campbell BrownHarris faces pivotal moment with Supreme Court battle Remote work poses state tax challenges Senate Democrats release report alleging Trump admin undermined fair housing policies MORE, New York Gov. Andrew Cuomo and Housing and Urban Development Secretary Julián Castro.

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Meanwhile, Minnesota Sen. Al Franken Alan (Al) Stuart FrankenGOP Senate candidate says Trump, Republicans will surprise in Minnesota Peterson faces fight of his career in deep-red Minnesota district Getting tight — the psychology of cancel culture MORE and New York Sen. Kirsten Gillibrand Kirsten GillibrandSunday shows preview: Justice Ginsburg dies, sparking partisan battle over vacancy before election Suburban moms are going to decide the 2020 election Jon Stewart urges Congress to help veterans exposed to burn pits MORE received 3 percent support each for the nomination.

With the 2020 election nearly four years away, early polls generally only show which candidates have the strongest name recognition, which would explain while Biden, Sanders and Warren are emerging as top picks for Democratic voters.

PPP notes that Booker, Cuomo, Castro, Brown and Gillibrand all have less than 50 percent name recognition with Democrats nationally.

In 2012, polls gave Sen. Marco Rubio Marco Antonio RubioOvernight Defense: Pentagon redirects pandemic funding to defense contractors | US planning for full Afghanistan withdrawal by May | Anti-Trump GOP group puts ads in military papers Democrats step up hardball tactics as Supreme Court fight heats up Press: Notorious RBG vs Notorious GOP MORE (R-Fla.) and New Jersey Gov. Chris Christie (R) large advantages, though they both ended their presidential bids early in the year.

However, polls also showed Hillary Clinton Hillary Diane Rodham ClintonDemocratic groups using Bloomberg money to launch M in Spanish language ads in Florida The Hill's Campaign Report: Presidential polls tighten weeks out from Election Day More than 50 Latino faith leaders endorse Biden MORE dominating the field of prospective Democratic candidates, which she won despite a strong challenge from Sanders.

Fifty-seven percent of Democrats polled said they want their candidate to be under the age of 60, and 77 percent said they want their candidate to be younger than 70.

Biden and Sanders are 74 and 75, respectively.

Only 25 percent of Democrats said they want their candidate to be someone who has run for president before, while 41 prefer someone who hasn't, and 34 percent said they are not sure one way or the other.

“There’s a tension for Democrats nationally,” said Dean Debnam, president of Public Policy Polling. “They want new blood, but their most well known and popular figures don’t exactly fit that mold. Of course they have a long time to get that all figured out.”