Former Vice President Joseph R. Biden has maintained a double-digit advantage over his nearest competitor for the Democratic presidential nomination, according to a survey taken after last week’s debate that also showed support for Sen. Elizabeth Warren ticked up a few points.
Mr. Biden was the top choice of 32% of potential Democratic primary voters, followed by Sen. Bernard Sanders of Vermont at 20% and Ms. Warren of Massachusetts at 18%, according to the Morning Consult poll released on Monday.
Support for Ms. Warren ticked up 2 points compared to last week, while Mr. Biden and Mr. Sanders each lost 1 point of support.
Sen. Kamala D. Harris of California was next at 6%, followed by Pete Buttigieg, mayor of South Bend, Indiana, at 5%, former Rep. Beto O’Rourke of Texas at 4%, and Sen. Cory A. Booker of New Jersey and entrepreneur Andrew Yang at 3% apiece.
Former Obama administration official Julián Castro, who took a shot at the 76-year-old Mr. Biden’s memory during the debate, saw his net favorability drop compared to last week’s survey.
Pre-debate, about 37% of respondents reported a favorable view of Mr. Castro, compared to 15% who had an unfavorable opinion.
In the new survey, 34% of respondents said they had a favorable view of him, compared to 24% who had an unfavorable opinion — though about four in 10 still said they either had never heard of him or had no opinion about him.
The overall survey of 7,487 registered voters who said they might vote in their state’s Democratic primary or caucus was taken from Sept. 13-15 and has a margin of error of plus or minus 1 percentage point.