Biden is now the clear favorite to win the 2020 presidential election

On November 3, 2020, a weeks-long presidential election between incumbent Republican Donald J. Trump and his Democratic challenger, former Vice President Joseph R. Biden, Jr., will end. As I write this, more than 23 million Americans—including yours truly—have already cast their ballots. This number is just over 1/6 of total votes cast in 2016.

Following an extremely contentious first presidential debate on September 29, and dueling town hall events on October 15, here is an updated assessment of the 2020 presidential election; you may find my previous assessment here. Assessments are based upon all publicly-available polls of the presidential election—nationally and by state, recognizing presidential elections are determined by the Electoral College—conducted since January 1, 2019.

A total of 606 national polls assessing Biden vs. Trump have been conducted since January 1, 2019,[1] of which:

• 499 have been conducted since January 1, 2020
• 140 have been conducted entirely since the end of the national party conventions on August 28
• 44 have been conducted entirely since the first presidential debate

The 70+ pollsters who have assessed this election at least once have an average B- FiveThirtyEight pollster rating, as do the 50+ pollsters who have assessed the election multiple times.

Figure 1 shows how Biden has fared monthly against Trump in 2020, using my weighted-adjusted polling averages (WAPA). I use pollster rating data to adjust for partisan lean (historic tendency to err more Democratic or Republican than other pollsters in analogous races) and quality.[2] I weight more recent polls higher, using the number of days since January 1, 2019 divided by 673, the number of days between January 1, 2019 and November 3, 2020. I then average two versions of WAPA: one treating polls by the same pollster as statistically independent, and one treating all polls by the same pollster as a single, time-weighted value; differences between estimates are usually negligible. Polls conducted after August 28, but before September 30, are weighted 1.5 times higher than prior polls, and polls conducted entirely after September 29 are weighted 3.0 times higher.

Figure 1

Using all polls conducted since January 1, 2019, Biden leads Trump nationally by 8.2 percentage points (“points”), with his lead rising to 8.8 points only using polls conducted since the conventions, and to 9.9 points only using the 46 polls with an October 2020 field date midpoint. Biden’s margin over Trump has risen from just over four percentage points in January and February, when he was fighting for the 2020 Democratic presidential nomination, to just under six points in the three months after Biden’s decisive win in the 2020 South Carolina Democratic presidential primary, to between seven and 10 points since June 1, the day protesters were forcibly cleared from Lafayette Square so Trump could pose in front of St. John’s Episcopal Church holding a copy of the Bible.

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Again, though, presidential elections are fought across 50 states and the District of Columbia (“DC”), with the plurality winner in each state/DC winning every electoral vote (“EV”) from that state. Now that SurveyMonkey—a D- pollster with a 5.0-point historic Democratic bias—has released a set of polls covering June, July, August and September, every state/DC has now been polled at least four times.

Table 1 reports two projected Democratic-minus-Republican margins and corresponding EV win percentage (“EV%”) for every state and DC: one using all polls conducted since January 1, 2019, and one using only polls conducted since the two national party conventions. The table is sorted from highest to lowest EV% using the larger set of polls. For margin and EV% calculations, see here.

Table 1: Projected 2020 Biden-Trump margins and likelihood of winning EV calculated two ways

State	Margin since 1/1/2019	EV%	Margin since 8/29/2020	EV%
DC	71.4	100.0%	70.7	100.0%
Hawaii	32.2	100.0%	34.6	100.0%
Vermont	26.8	100.0%	23.6	100.0%
California	28.4	100.0%	28.5	100.0%
Maryland	29.4	100.0%	30.9	100.0%
Massachusetts	34.0	100.0%	29.1	100.0%
New York	27.1	100.0%	31.4	100.0%
Rhode Island	16.8	100.0%	23.4	100.0%
Illinois	14.9	100.0%	19.0	100.0%
Connecticut	20.3	100.0%	20.3	100.0%
Delaware	21.0	100.0%	20.8	100.0%
Washington	21.1	100.0%	21.1	100.0%
New Jersey	19.3	100.0%	19.5	100.0%
Oregon	16.0	99.9%	16.2	99.9%
New Mexico	11.8	99.9%	12.9	99.9%
Maine	12.7	99.8%	14.0	99.9%
Colorado	11.6	99.7%	11.4	99.7%
Virginia	10.5	99.6%	12.1	99.7%
Minnesota	8.5	99.4%	8.0	99.3%
New Hampshire	7.8	99.0%	8.9	99.4%
Michigan	7.2	98.9%	7.2	98.9%
Wisconsin	5.8	96.8%	6.6	98.2%
Pennsylvania	5.5	96.1%	5.8	96.7%
Nevada	4.5	92.0%	5.3	95.3%
Florida	2.8	81.9%	3.1	83.9%
Arizona	2.8	81.9%	3.4	86.2%
North Carolina	1.8	71.7%	1.9	73.4%
Ohio	0.0	49.5%	-0.8	39.0%
Georgia	-0.1	48.8%	0.0	49.7%
Iowa	-0.8	39.0%	-0.7	39.7%
Texas	-2.2	25.0%	-2.1	25.5%
Alaska	-5.6	3.5%	-5.6	3.6%
Missouri	-6.9	1.6%	-6.9	1.8%
South Carolina	-7.7	0.9%	-7.6	1.0%
Mississippi	-12.8	0.5%	-11.2	0.6%
Indiana	-10.3	0.4%	-9.1	0.6%
Montana	-8.6	0.4%	-8.8	0.4%
Kansas	-12.2	0.2%	-11.9	0.2%
Louisiana	-12.3	0.1%	-13.0	0.1%
Nebraska	-17.3	0.0%	-19.0	0.0%
South Dakota	-22.1	0.0%	-19.5	0.0%
Tennessee	-17.3	0.0%	-19.5	0.0%
Arkansas	-18.0	0.0%	-24.2	0.0%
Alabama	-18.9	0.0%	-20.1	0.0%
Kentucky	-18.9	0.0%	-20.9	0.0%
North Dakota	-23.3	0.0%	-21.3	0.0%
Utah	-15.0	0.0%	-15.2	0.0%
Idaho	-26.0	0.0%	-26.7	0.0%
West Virginia	-21.5	0.0%	-16.7	0.0%
Oklahoma	-27.2	0.0%	-27.0	0.0%
Wyoming	-42.7	0.0%	-36.4	0.0%

With just 17 days until Election Day 2020, Joe Biden is the clear favorite to be elected the 46^th president of the United States. The most direct way for Biden to win the Electoral College is to win the 232 EV from the states won by Democratic presidential nominee Hillary Clinton won in 2016, then add Michigan (98.9%), Wisconsin (96.8-98.2%) and Pennsylvania (96.1-96.7%); he could even lose Nevada (92.0-96.2%) and still win 273 EV, three more than necessary. Taking the product of the likelihood of victory for the states totaling 273 EV yields a minimum 89.5% probability Biden wins the Electoral College using all polls, which rises to 91.8% using only post-convention polls. These are very rough probabilities given how correlated voting behavior is across demographically-similar states, though they are broadly in line with other public estimates.

Moreover:

• He is at least a 92.0% favorite in enough states—and by margins of at least 4.5 points—to earn him 278 or 279 EV, depending on what happens in Maine, which, along with Nebraska, allocates two EV to the statewide winner and one each to the winner of its Congressional districts. At this point, Biden would already have won the presidency.
• He is favored better than 4-1 to win the 11 EV of Arizona and the 29 EV of Florida, by around three points each, increasing Biden’s total to 318 or 319 EV.
• He is favored 5-2 to win North Carolina, by a hair under two points, for an additional 15 EV, increasing Biden’s total to 333 or 334 EV.
• The 40 combined EV of Ohio, Georgia and Iowa are essentially toss-ups, with projected margins of less than one point, increasing Biden’s total to between 339 and 375 EV; Biden has a roughly 81% chance of winning at least one of them. That said, winning Iowa would require a winning a solid majority of undecided voters, Ohio has been trending slightly away from Biden, and Georgia is literally 50-50.

Plus, it might take only a sharp break by undecided voters and a modest polling error for Biden to win the ultimate prize—Texas (-2.1). Thus, while something in the mid-300’s currently appears the most likely EV total for Biden, 413 (or more) EV cannot be discounted.

Using the simplistic—perhaps even simple-minded—method of multiplying Biden’s probability of winning each state by its EV, then summing, yields a “projected” EV total of just under 350 EV using both sets of polls, essentially adding Michigan, Pennsylvania, Wisconsin, Florida, Arizona, North Carolina, and one of Ohio/Georgia/Iowa to the states Clinton won.

Biden’s lead looks even stronger after making either of two historically-valid assumptions; calculation use all polls conducted since January 1, 2019:

Polls systematically overestimate Biden’s margins by 3.0 points.

In this scenario, Biden’s projected EV drops to 300.8, 28.8 more than required, with a minimum “path of least resistance” probability of 51.0%. He would be favored at least 78.8% to win in enough states to win 273 EV. Thus, even if Biden “only” wins the national popular vote by 5.2 points, he would likely still prevail, though the decisive states of Wisconsin and Pennsylvania would be decided by relatively narrow margins, with all votes possibly not counted for a week or more. That Biden could win the national popular vote by more than five points, yet still only be a modest favorite to win at least 270 EV, demonstrates the recent Republican advantage in the Electoral College.

Polls systematically underestimate Biden’s margins by 3.0 points.

In this scenario, Biden’s projected EV are a landslide-level 390.3, 120.3 more than necessary, with a minimum “path of least resistance” probability of 97.2%.  He would be favored at least 80% to win enough states to earn 368 EV, while being a 3-1 favorite in Iowa, for a total of 374 EV. Biden would even be a slight favorite (61.7%) in Texas, which he would be projected to win by 0.8 points. Biden would also have a 20.4% chance of winning Alaska’s 3 EV and a 10.4% chance of winning Missouri’s 10 EV. The last presidential candidate to come close to 426 EV was Republican George H. W. Bush, who won 426 EV in 1988.

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None of this is to say Biden is guaranteed to be elected the next president of the United States. Even with the massive surge in early voting, delays in mail delivery—allegedly orchestrated by the Postmaster General—could leave millions of votes uncounted because they did not arrive by November 3. Pennsylvania, the most likely “tipping point” state—the one giving either Biden or Trump the necessary 270 EV when states are ordered most to least Democratic—is already showing the strain of trying to establish absentee voting on the fly. Moreover, while Biden’s national polling lead has ranged between seven and 10 points since June 1, a last-minute “October surprise” could erase this lead, though this “e-mails” story is unlikely to be it.

Nonetheless, unlike Clinton in 2016, Biden has a sufficiently-wide range of paths to 270 EV that I estimate he is at least a 92% favorite to be elected president of the United States on November 3, 2020—or whenever ballots are ultimately counted.

Until next time…please stay safe and healthy…

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[1] I limit iterations of tracking polls only to those with non-overlapping field dates.

[2] I halve the number value assigned to a letter grade for any poll conducted since June 1, 2020 which samples adults instead of registered or likely voters.