#NEW I did some math & wrote a piece about what trouble with the USPS and vote-by-mail actually means in November. The takeaway is that above-average VBM usage & ballot rejection rates could cost Biden 0.6 points in vote margin on average. Thread economist.com/united-states/…
I was particularly irked by some of the less-thought-through analyses on vote-by-mail going around in recent weeks. No, the effects aren't large enough to decrease Biden's vote margin by 4 points except in the most extreme cases of rejection rates and partisan VBM composition.
But focusing on the doomsday scenario probably obscures the danger.
If VBM usage is high & mostly Democratic (polls put the composition of postal ballots at 70-80% Democratic right now), & ballot rejection rates are slightly higher than average, Biden could easily lose 1-2pts.
If VBM usage is high & mostly Democratic (polls put the composition of postal ballots at 70-80% Democratic right now), & ballot rejection rates are slightly higher than average, Biden could easily lose 1-2pts.
We came up with this number by simulating 100k different combinations of (a) VBM usage, (b) ballot rejection rates, (c) partisan composition of postal votes and (d) how close the election will be nationally. (Props to @jon_m_rob for doing similar crunching a few weeks back.) 
These simulations give us a distribution of possible decreases in Joe Biden's vote margin. If VBM goes down or rejection rates are about normal, that deficit is less. If postal ballots are more Democratic and rejection rates go up, he loses more. Those scenarios look like this:
We can also take all those values and plug them into our election forecast. This can tell us a variety of things, like whether factoring in USPS trouble creates more electoral uncertainty (yes) that hurts Biden (yes), and whether that hurts more in swing states (mixed evidence).
AND we can use the sims to figure out the chance that final vote margin in a decisive state lands inside the recount threshold (typically 0.5pts, but rules vary by state). The probability of a recount nearly doubled from 5 to 9% after adding in the VBM scenarios. Right-hand panel
Now, to be extra clear, this is not electoral doomsday.
The average decrease in Biden's margin is just 0.6 pts, and that assumes slightly higher-than-average VBM rejection rates will carry over from the 2020 primary to the general.
The eventual deficit could also be smaller!
The average decrease in Biden's margin is just 0.6 pts, and that assumes slightly higher-than-average VBM rejection rates will carry over from the 2020 primary to the general.
The eventual deficit could also be smaller!
If the turmoil at the USPS continues, fewer politically-active Dems will probably try to cast postal votes. If the election stays this lopsided, even a large deficit won't "matter" (it will be a huge stain on democracy, of course, but won't change the outcome).
But if the situation with the USPS DOES improve, there is much less cause for alarm there. That puts the remaining pressure on local election workers, who can be better trained to follow new VBM rules and can do their jobs better with more poll volunteers. eac.gov/voters/become-…
My piece should help calibrate expectations for this. It is more likely that trouble with VBM causes a negligible excess impact on rejection rates (disproportionately impacting Democratic votes) than it is that it causes the doomsday scenario.
But the more reasonable scenario — a recount in a decisive state, attributed almost entirely to problems with postal voting — could cast the election into a prolonged legal battle. Remember 2000? There is a reasonable and nonzero chance that we relive Bush v Gore.
One final thing: All this trouble underscores a larger point about how bad American election administration is. We need an ambitious federal overhaul of voting technology and a groundswell in support for expanded access. And we need more people volunteering as poll workers!
