Biden’s dominance in public polling has diminished since August, when the previous Suffolk survey showed he was the favorite of 32 percent of likely Democratic voters and only 14 percent preferred the second-place Warren. Now, his edge has been slashed to 9 percentage points from 18.

The latest poll also moves Rep. Tulsi Gabbard of Hawaii, who garnered 4 percent support, closer to qualifying for two debates. She needs to reach a 3 percent threshold in one more poll approved by the Democratic National Committee before Nov. 13 to participate in the upcoming forum in Atlanta on Nov. 20. If the congresswoman qualifies, she will become the 10th candidate set to appear onstage next month.

Gabbard has halfway met the polling requirements for the Dec. 19 debate, to be hosted by POLITICO and PBS in Los Angeles, and needs to hit 4 percent in two additional DNC-approved polls by Dec. 12. She must also clear a donor threshold of 200,000 contributors for December, however. Her campaign did not immediately respond to an inquiry about whether she had crossed the new donations mark; as of mid-September, she had 172,000 donors.

So far, only four candidates — Biden, Buttigieg, Sanders and Warren — have qualified for the December debate. Harris is likely to join them, despite polling at only 3 percent in the Suffolk survey, needing just one more poll to qualify.

The USA TODAY/Suffolk University poll was conducted Oct. 23-26, surveying 399 likely Democratic voters. The margin of error is plus or minus 4.9 percentage points.