Oct. 28, 2019 — We covered a series of polls Friday that were projecting former Vice President Joe Biden regaining his early campaign advantage. On closer review, however, it was found that only the small sample polls with a large error factor were yielding the unusual Biden margins. The large sample surveys found a much closer split among the top three candidates: Biden and Sens. Elizabeth Warren (D-MA) and Bernie Sanders (I-VT).
Several new polls were just released during the latter half of the month, all conducted after Oct. 15 with large or statistically acceptable sample sizes, yet the conclusions drawn nationally and in key states were very different.
The following table compares the analyzed polls, which are national, and two each from California and Iowa. Both of the states have unique positions in the Democratic nomination process. Iowa is the first voting state, and thus a trendsetter, while California has the largest contingent of delegates, 416 on the first ballot and 495 when the Super Delegates are added to the total.
The new Quinnipiac University survey released last Thursday (Oct. 17-21; 1,587 US registered voters; 713 likely Democratic primary voters) finds Sen. Warren capturing the national lead, with Biden and Sen. Sanders following. Mayor Pete Buttigieg breaks into double digits in a country-wide poll for the first time since early June.
This result, however, directly conflicts with both the Morning Consult track (Oct. 16-20; 11,521 likely Democratic primary voters; online US) and Survey USA’s most recent national poll (Oct. 15-16; 1,071 US likely Democratic primary voters), both of which report consistent result spreads and a Biden edge.
Inconsistencies are also present in Iowa and California. The new Civiqs/Iowa State University poll (Oct. 18-22; 598 likely Iowa Democratic primary voters) returns the worst numbers for Biden of any poll either nationally or in a state.