Oct. 25, 2019 — A series of recently released national political polls finds former Vice President Joe Biden re-establishing the type of horse race leads over the Democratic field that he enjoyed before the debate process first began. Yet, how reliable are the polls?
CNN, YouGov, Emerson College, and HarrisX, all report new data and see Biden again posting significant leads, two of which are well beyond the polling margin of error.
CNN (Oct. 17-20; 424 US Democratic registered voters) gives the ex-VP a 34-19-16 percent lead over Sens. Elizabeth Warren (D-MA) and Bernie Sanders (I-VT). HarrisX (Oct. 21-22; 440 US registered Democratic voters) finds the Biden lead reaching 27-19-14 percent over Warren and Sanders. Emerson College (Oct. 18-21; 430 US Democratic likely voters) sees a similarly close cut among the top three candidates, but they find Sen. Sanders slipping past Warren into second place. The Emerson split shows Biden up 27-25-21 percent over Sanders and Warren, respectively.
Looking more closely at the polling methodology for each, we find that all three of these surveys have very low sample sizes, which means the error factor is high. The respective respondent universes are only between 424 and 440 people from which to derive a national trend. These numbers are more typically found in a congressional district or small state survey.
The YouGov poll (Oct. 20-22; 628 US Democratic likely voters) used a larger national sample and found a much tighter standing among the candidates, but with the prevalent Biden-Warren-Sanders order intact through a 24-21-15 percent result. In all of the aforementioned surveys, no other candidate reaches double-digit support.
There are two other national polls with large sample sizes conducted during the relative period. The Morning Consult tracking survey (Oct. 16-20; 11,521 US likely Democratic primary voters, online) also finds Biden holding a significant advantage, 30-21-18 percent, over Sens. Warren and Sanders.
Survey USA (Oct. 15-16; 1,071 US Democratic likely primary voters), in similar fashion to Morning Consult, brandishes a strong sample and methodology yet arrives at a similar conclusion to the small sample polls. They also find Biden expanding his lead to 32-22-17 percent over Sens. Warren and Sanders, respectively.
The poll grouping has different methodologies and a wide range of sampling universes, but they all generally arrive at the same basic conclusion. That is, Biden appears to be on the upswing and again has a discernible national polling advantage.
Sensing Biden momentum at this time when the Ukraine controversy has touched him and his son is an interesting trend, but it could signify that the strong Democrats are rallying around him in a similar manner to how the base Trump supporters back the president.
On the other hand, the poll could simply be reflecting normal ebbs and flows in a national campaign featuring a long duration. Before this set of studies were released, it was becoming clear that Sen. Warren was rapidly gaining strength, but the new data again reminds us of how fluid these modern era campaigns often become.
Possibly the most significant takeaway, however, is that we again see a definitive three-way race among Democrats since it is especially telling that no other candidate even reaches the 10 percent plateau in any of the surveys regardless of sampling size or methodology.
It is reasonable to expect that the polling patterns will change over the coming months, and though Biden could well be re-establishing the lead now less than four months before Iowans cast the first votes on Feb. 3, it appears this nomination contest is far from over. It remains conceivable that the intra-party battle could go all the way to the Democratic National Convention before any one of the candidates can cobble together the necessary majority coalition needed to clinch the party nomination and the right to face President Trump in the general election.