NBC/Wall Street Journal Poll that Shows Biden Leads Trump by 14 Points Oversampled Democrats

The NBC/Wall Street Journal Poll released on Sunday that shows Democratic presidential candidate Joe Biden with a 14 point lead in the national popular vote over President Donald Trump, 53 percent to 39 percent, significantly oversampled Democrats.

The poll of 800 registered voters was conducted between September 30 and October 1 and has a margin of error of 3.46 percent.

Thirty-five percent of poll respondents self-identified as Democrats, while only 27 percent self-identified as Republican, and 32 percent self-identified as Independents, resulting in a survey sample that was Democrat +8, a significantly higher sampling of Democrats than measured in the most recent national Gallup Poll of party affiliation. That poll, (conducted between August 31 and Sept 13), found that 29 percent of Americans self-identified as Republican, 30 percent self-identified as Democrat, and 40 percent self-identified as Independents, resulting in an actual national partisan breakdown of Democrat +1.

In other words, the NBC/Wall Street Journal Poll includes five percent more Democrats and two percent fewer Republicans than the actual national population, for a net oversampling of Democrats of seven percent.

In contrast, the IBD/TIPP Poll released on Friday, which shows Biden with just a three point lead over Trump–within the poll’s margin of error–was taken from a weighted sample of likely voters with a partisan breakdown of Democrat +1, the same as September 2020 national Gallup Poll of party affiliation of Democrat +1.  Forty percent of poll respondents were Democrats, 39 percent were Republican, and 20 percent were Independents.

Similarly, the Sunday Express/Democracy Institute Poll released on Saturday that shows Trump with a one point lead over Biden has a national turnout model of 37 percent Democrat and 35 percent Republican, or Democrat +2.

The Real Clear Politics Average of Polls currently shows Biden with an 8.5 point lead over President Trump with a month to go until the election on November 3.

Given this oversampling of Democrats in the NBC/Wall Street Journal Poll, the poll’s results on other questions are not surprising:

• 49 percent said Joe Biden did a better job at the September 29 presidential debate, while 24 percent said Donald Trump did a better job.
• 19 percent said the debate made them more likely to support Joe Biden, while 6 percent said the debate made them more likely to support Donald Trump.
• 55 percent said Joe Biden would do a better job at dealing with race relations, compared to 26 percent who said Donald Trump would do a better job.
• 58 percent said Joe Biden has the right temperament to be president, compared to 26 percent who said Donald Trump had the right temperament
• 53 percent said Joe Biden will do a better job dealing with health care, compared to 36 percent who said Donald Trump would do a better job with health care.
• 41 percent said Joe Biden has the necessary mental and physical health to be president, compared to 40 percent who said Donald Trump has those qualities.
• 45 percent said Joe Biden will do a better job dealing with crime and violence, compared to 41 percent who said Donald Trump would to a better job dealing with crime and violence.

In only one area did poll respondents believe Donald Trump will do a better job than Joe Biden.

Forty-eight percent said Donald Trump will do a better job dealing with the economy, compared to 41 percent who said Joe Biden will do a better job dealing with the economy.

With one month to go until election day, a flurry of new national and battleground state polls will be released each remaining day. Close scrutiny of each poll’s methodology and sampling techniques is a key element for every informed reader.