These charts reflect the results of the newly-released Economist / YouGov Poll -- done between August 10th and 13th of a national sample of 1,500 adults (including 1,127 registered voters). The margin of error was 3 points for registered voters.
The top chart shows who the 592 people likely to vote in a Democratic primary/caucus are currently supporting (margin of error unknown). It has Joe Biden (21%) and Elizabeth Warren (20%) in a virtual tie for first place. Bernie Sanders (16%) and Kamala Harris (8%) were third and fourth, while Beto O'Rourke and Pete Buttigieg both registered 5%. No one else was able to top 2%.
The bottom chart shows the generic presidential vote among the registered voters. Currently, a generic Democrat would beat Trump by about 11 points.