Former first lady Michelle Obama Michelle LeVaughn Robinson ObamaMichelle Obama: 'Don't listen to people who will say that somehow voting is rigged' Michelle Obama and Jennifer Lopez exchange Ginsburg memories Social media platforms put muscle into National Voter Registration Day MORE tied with former Vice President Joe Biden Joe BidenOmar fires back at Trump over rally remarks: 'This is my country' Trump mocks Biden appearance, mask use ahead of first debate Trump attacks Omar for criticizing US: 'How did you do where you came from?' MORE as the top choice among Democratic voters when asked who should be the party's nominee in 2020.

A Hill-HarrisX poll released Tuesday found that 25 percent of Democrats said they would back Obama in the party primary over nine other declared or potential candidates, including Sens. Bernie Sanders Bernie SandersButtigieg stands in as Pence for Harris's debate practice Bernie Sanders warns of 'nightmare scenario' if Trump refuses election results Harris joins women's voter mobilization event also featuring Pelosi, Gloria Steinem, Jane Fonda MORE (I-Vt.), Kamala Harris Kamala HarrisButtigieg stands in as Pence for Harris's debate practice First presidential debate to cover coronavirus, Supreme Court Harris joins women's voter mobilization event also featuring Pelosi, Gloria Steinem, Jane Fonda MORE (D-Calif.), Elizabeth Warren Elizabeth WarrenHarris joins women's voter mobilization event also featuring Pelosi, Gloria Steinem, Jane Fonda Judd Gregg: The Kamala threat — the Californiaization of America GOP set to release controversial Biden report MORE (D-Mass.), and former Rep. Beto O’Rourke (D-Texas).

Obama has said she is not running, and Biden has not announced whether he will launch another White House bid.

Harris came in third among Democratic voters, with 12 percent saying they would support her. Sanders was a close fourth, at 11 percent. O’Rourke, former New York City Mayor Michael Bloomberg, Warren, and Sens. 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 (D-N.J.), Amy Klobuchar Amy KlobucharSocial media platforms put muscle into National Voter Registration Day Battle lines drawn on precedent in Supreme Court fight Sunday shows - Ruth Bader Ginsburg's death dominates MORE (D-Minn.) and Sherrod Brown Sherrod Campbell BrownSenate Democrats release report alleging Trump admin undermined fair housing policies Bipartisan praise pours in after Ginsburg's death Emboldened Democrats haggle over 2021 agenda MORE (D-Ohio) all failed to exceed 6 percent.

Biden and Obama garnered 23 percent and 22 percent, respectively, when factoring in independent voters, who are allowed to vote in many state primary elections.

When combining Democratic and independent voters, Sanders received 12 percent, followed by 8 percent for Harris.

Molly Murphy, a partner at Democratic consulting firm ALG Research, said Obama's popularity is helped in large part because she has never thrown her hat into the ring.

"Because she's never been a candidate, she's never been on the ballot, she's avoided a certain degree of scrutiny that candidates face. And so she's all icing for people, it's all good," Murphy said Tuesday on "What America's Thinking," Hill.TV's show about public opinion and polling.

In the Hill-HarrisX poll, 12 percent of independents and Democrats combined said they preferred another candidate, beyond the choices that were offered, suggesting some dissatisfaction among non-Republican voters with the field of declared and potential candidates.

A November Hill-HarrisX poll found that 14 percent of Democratic respondents picked "none of the above" when asked to choose between Warren, Biden, Sanders, Booker, Harris, Bloomberg and former Democratic presidential nominee Hillary Clinton Hillary Diane Rodham ClintonButtigieg stands in as Pence for Harris's debate practice Senate GOP sees early Supreme Court vote as political booster shot Poll: 51 percent of voters want to abolish the electoral college MORE.

Obama's surprise appearance at the Grammy awards this month promoted some speculation about a possible 2020 bid. In December, the former first lady said that she had "never" considered a political career and that she had no intention of running for office.

The Hill-HarrisX survey was conducted Feb. 17-18 among a nationally representative sample of registered voters. The overall survey has a sampling margin of error of 3 percentage points.

The group of Democratic respondents has a sampling margin of error of 5 percentage points, and the Democratic and independent set has a sampling margin of error of 4 percentage points.

—Matthew Sheffield