Poll: 33 percent of voters undecided on who won third Democratic debate

More people said they were uncertain about who won last week's Democratic presidential debate than picked a specific winner, according to a new Hill-HarrisX poll released on Monday.

Thirty-three percent of people said they were unsure which of the the 10 candidates on the stage won the debate, a figure more than a third higher than the 20 percent of Democratic voters who said former Vice President Joe Biden was the winner and did the best. 

Twelve percent thought that Sen. Elizabeth Warren (D-Mass.) had the best performance, and 9 percent picked Sen. Bernie Sanders (I-Vt.).

Sen. Kamala Harris (D-Calif.) came in fourth place, with 7 percent saying she did the best in the poll released Monday.

Former Texas Rep. Beto O'Rourke (D) and Sen. Cory Booker (D-N.J.) tied for fifth place, with 5 percent. 

South Bend, Ind., Mayor Pete Buttigieg, tech entrepreneur Andrew Yang, and former Housing and Urban Development Secretary Julián Castro were the only other candidates to receive at least 2 percent of the vote or higher.

The debate was the first time the Democratic field has been contained to one stage and one night of debates.

The biggest moment of the night came when Castro, during an argument over health care with Biden, appeared to take a jab at the front-runner's age by repeatedly saying, "Are you forgetting what you said two minutes ago" to the 76-year-old former vice president.

The debate also included tough exchanges over health care, though overall the debate did not feature as many heated discussions as earlier debates.

The Hill-HarrisX poll was conducted online among 371 registered voters between Sept. 13 and 14. It has a margin of error of plus or minus 5.5 percentage points.

-Tess Bonn