The survey, released early Tuesday, shows Biden still leads the crowded pack of Democrats vying for the party’s nomination with 32 percent support.
However, his support is now 7 points lower than it was in an April CNN poll shortly after his formal entry in the race, when 39 percent said they supported him.
South Bend, Ind. Mayor Pete Buttigieg and former Texas Rep. Beto O’Rourke (D) both received 5 percent support, according to the poll.
Biden’s commanding lead in the polls has been putting pressure on Democratic lawmakers to endorse the former Delaware senator.
The CNN poll of 1,006 adults was conducted by SSRS from May 28 through 31. It has a margin of error of 3.8 percentage points.