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 BidenJoe BidenSupport for impeachment inches up in poll Overnight Defense: Trump's Syria envoy wasn't consulted on withdrawal | McConnell offers resolution urging Trump to rethink Syria | Diplomat says Ukraine aid was tied to political investigations Democrats say they have game changer on impeachment MORE was the winner and did the best. 

Twelve percent thought that Sen. Elizabeth WarrenElizabeth Ann WarrenOvernight Health Care — Presented by Partnership for America's Health Care Future — ObamaCare premiums dropping for 2020 | Warren, Buttigieg shift stances on 'Medicare for All' | Drug companies spend big on lobbying Mellman: Trumping peace and prosperity On The Money: Waters clashes with Trump officials over 'disastrous' housing finance plan | Dems jump into Trump turf war over student loans | House passes bill targeting anonymous shell companies MORE (D-Mass.) had the best performance, and 9 percent picked Sen. Bernie SandersBernie SandersOvernight Health Care — Presented by Partnership for America's Health Care Future — ObamaCare premiums dropping for 2020 | Warren, Buttigieg shift stances on 'Medicare for All' | Drug companies spend big on lobbying Mellman: Trumping peace and prosperity Tlaib to join Sanders at campaign rally in Detroit MORE (I-Vt.).

Sen. Kamala HarrisKamala Devi HarrisSaagar Enjeti: Warren, Buttigieg don't stand a chance against Trump Warren overtakes Sanders in new poll The Hill's 12:30 Report: Trump faces backlash for comparing impeachment to 'lynching' MORE (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 BookerCory Anthony BookerProgressive commentator: Voters becoming weary of Warren policy proposals Saagar Enjeti: Warren, Buttigieg don't stand a chance against Trump The Hill's 12:30 Report: Trump faces backlash for comparing impeachment to 'lynching' MORE (D-N.J.) tied for fifth place, with 5 percent. 

South Bend, Ind., Mayor Pete ButtigiegPeter (Pete) Paul ButtigiegOvernight Health Care — Presented by Partnership for America's Health Care Future — ObamaCare premiums dropping for 2020 | Warren, Buttigieg shift stances on 'Medicare for All' | Drug companies spend big on lobbying Poll: Biden holds 2 point lead over Sanders nationally Saagar Enjeti: Warren, Buttigieg don't stand a chance against Trump MORE, tech entrepreneur Andrew YangAndrew YangSaagar Enjeti: Warren, Buttigieg don't stand a chance against Trump Warren overtakes Sanders in new poll Poll: Biden leads Warren by 15 points in California MORE, 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