This chart reflects the results of the latest Economist / YouGov Poll -- done between December 7th and 10th of a national sample of 497 likely Democratic primary voters. No margin of error was given just for this group, but it would likely be in the 5 point range.
The chart above reflects the results of the latest Quinnipiac University Poll -- done between December 4th and 9th of a national sample of 665 likely Democratic primary voters, with a 3.8 point margin of error.
