With the second Democratic presidential nomination debates scheduled for the evenings of Tuesday, July 30, 2019 and Wednesday, July 30, 2019, here is an updated assessment of the relative position of the 25 declared candidates; because United States House of Representatives member (“Representative”) Eric Swalwell of California dropped out of the race on July 8, 2019, a spot opened on the debate stage for Montana Governor Steve Bullock on the first night of the debates. Among those not making the cut are billionaire activist Tom Steyer, who declared his candidacy on July 9, 2019.
To learn how I calculate NSW-WAPA (national-and-state-weighted weighted-adjusted polling average), please see here. Note that I recently altered my methodology slightly: within my post-early-state weighted average of each candidate’s WAPA, I now weight the nine states scheduled to hold their nomination contests on March 3, 2019 (“Super Tuesday”) twice as much as all subsequent contests.
And, of course, here is the July 2019 lighthouse photograph in my Down East 2019 Maine Lighthouses wall calendar.
Table 1 aggregates data from 129 national polls (including 30 weekly Morning Consult tracking polls) released since January 1, 2019; 18 Iowa Caucuses polls; 20 New Hampshire Primary polls; three Nevada Caucuses polls; 17 South Carolina polls; 30 Super Tuesday polls and 30 polls from 12 other states. This makes a total of 247 polls, up from 176 last month.
Table 1: National-and-state-weighted WAPA for declared 2020 Democratic presidential nomination candidates
Were the Democratic National Committee using NSW-WAPA to determine eligibility for the July Democratic debates, Steyer would be on stage instead of New York City Mayor Bill de Blasio. Still, these are differences of fractions of a 1/10 of a percentage point—a coin flip would be just as effective.
It is clear the first Democratic presidential nomination debates measurably impacted the relative standing of the candidates. Thus, while he remains the (nominal) front-runner, especially in South Carolina (36.8%, well ahead of Vermont Senator Bernie Sanders at 13.0%), former Vice President Joe Biden saw his support drop 2.6 percentage points (“points”) to 28.6% in just over one month. This is a substantial amount given that my methodology (slow to discount older polls; weighs early state polls much higher than national polls) mitigates against rapid polling fluctuations. Other candidates with notable declines are Sanders (-1.1 points to 16.5%), former Texas Representative Beto O’Rourke (-0.7 points) and New Jersey Senator Cory Booker (-0.5 points).
By contrast, Massachusetts Senator Elizabeth Warren continues her steady climb, from 8.5% at the beginning of June, to 11.3% at the end of June to 12.6% at the end of July; she is close to challenging Sanders for the second spot behind Biden. California Senator Kamala Harris, meanwhile, has moved back into fourth place behind Warren, jumping 0.9 points to 9.2%. South Bend, Indiana Mayor Pete Buttigieg also climbed 0.6 points (to 8.1%), while a modest increase for entrepreneur Andrew Yang (1.1%) now makes him one of only nine candidates with an NSW-WAPA higher than 1.0.
At this point, fully three-quarters of those likely/eligible to vote in a 2020 Democratic presidential primary or caucus choose one of just five candidates: Biden, Sanders, Warren, Harris and Buttigieg. Another 8.1% choose O’Rourke, Booker, Minnesota Senator Amy Klobuchar and Yang, with fully 13.3% (up 2.0 points) undecided or choosing an unlisted candidate. The remaining 16 candidates are divvying up just 3.7% between them.
A more apples-to-apples way to measure the (short-term) impact of the June Democratic debates is to compare support for each candidate in poll—conducted by the same pollster—in June 2019 (end date no later than June 25, 2019) to those with a start date no earlier than June 28, 2019. Meeting these criteria are eight national polls, two Iowa Caucuses polls, two New Hampshire Primary polls, two South Carolina Primary polls and one Texas poll. For ease of presentation, Table 2 presents data only for the 11 candidates with an NSW-WAPA of 0.5 or higher (including Hawaii Representative Tulsi Gabbard, former Secretary of Housing and Urban Development Julián Castro). Values listed are simple arithmetic averages; weighting by pollster quality or time between polls made little difference.
Table 2: Average change in polls from the same pollster before and after June 2019 Democratic presidential debates:
Examined this way, support for Biden in public polls dropped fully 7.9 points from the month prior to the June 2019 Democratic debates to the month after those debates, almost exactly mirroring the 7.7-point increase for Harris. Moreover, the 3.0-point increase for Warren equals the sum of the declines for Sanders (-1.9 points) and Buttigieg (-1.1 points). Also noticeably declining were O’Rourke (-1.4) and Booker (-0.7), while Castro had a modest increase (+0.7). The percentage not choosing a listed candidate actually dropped by a not-insignificant 1.0 points.
To the extent that the polling for the 2020 presidential election between a named Democrat and Republican Donald J. Trump changed, it is due to the modestly-increased likelihood that someone other than Biden (who would hypothetically beat Trump nationally by 8.3 points) and Sanders (by 5.2 points) will be the 2020 Democratic presidential nominee. Thus, once you weight for the likelihood of being the nominee, the Democrat would beat Trump by 3.4 points. This is actually slightly higher than the median Democratic presidential margin (+3.0 points) in the previous six presidential elections, which include three elections with an incumbent seeking reelection and three elections with no incumbent. However, once you exclude Biden and Sanders, the margin over Trump decreases to 0.4 points; Warren would hypothetically win by 1.4 points and Harris by 0.9 points, while Buttigieg would lose by 1.5 points.
Still, given that state-level results actually determine the winner of a presidential election (via the Electoral College), it is more informative to look to those polls, where they are publicly-available. Using my 3W-RDM, a measure of how much more or less Democratic a state’s voting is relative to the nation as a whole, this polling implies Democrats would win the national popular vote by between 2.4 (excluding former Vice President Joe Biden and Vermont Senator Bernie Sanders) and 5.3 (including Biden and Sanders) points on average. Most encouraging to Democrats should be the polls from Texas (R+15.3), which show a very close race, implying a 12-14-point win nationally for Democrats; these polls confirm strong opportunities for Democrats in the southwest. By contrast, however, a few polls from Democratic-leaning Maine (D+5.9) and Nevada (D+2.0) imply Democrats would lose nationwide by 2-5 points. Those are the exceptions, however, to what is generally encouraging news for Democrats in 2020.
Enjoy the debates!
Until next time…
 Essentially, polls are weighted within areal units (nation, state) by days to the nominating contest and pollster quality to form a unit-specific average, then a weighted average is taken across Iowa (weight=5), New Hampshire (5), Nevada (4), South Carolina (4), the time-weighted average of all subsequent contests (2) and nationwide (1).
 Alabama, California, Colorado, Massachusetts, Minnesota, North Carolina, Tennessee, Texas, Virginia
 As of this writing, I have at least one poll from (in chronological order) Maine, Michigan, Mississippi, Missouri, Ohio, Arizona, Florida, Georgia, Wisconsin, Pennsylvania, Indiana and Oregon
 Primarily from California (13) and Texas (7)
 Primarily Florida (9)
 This does include polls that limit the number of candidates queried.
 Emerson College, Morning Consult Tracking, YouGov, Reuters/Ipsos, Change Research, Quinnipiac University, CNN/SSRS, Fox News
 Change Research, YouGov
 Change Research, YouGov
 Change Research, YouGov
 From Pennsylvania, New Hampshire, Wisconsin, Michigan, North Carolina, Texas, Iowa, Arizona, South Carolina, Minnesota, Nevada, Massachusetts, Florida, New York, Kentucky, Maine, Ohio.