A new poll by Opinium, for the Guardian, shows Biden winning the popular vote 57-40, i.e. a 17 point advantage. Even though several recent polls have shown double-digit leads, few have gone past +10, and no others have gone beyond +13 (+14 for the USC/Dornstrife panel).
This makes it an outlier. If it were absurd fantasy, I wouldn’t post about it, because why get people’s hopes up for nothing? But it is not. Here’s why:
In 538’s national vote poll history for the last few months, two things stand out: the narrow range of Trump’s numbers, and the wide range of Biden’s. Since mid-August, Trump’s numbers have been in the low forties, say between 40 and 43, occasionally dipping lower, a few times reaching 45-46. Biden’s numbers have ranged from 45 to 55, occasionally higher, occasionally lower. How is that discrepancy explained?
The Biden-Trump margin, as usually reported, is misleading. There is always a third candidate, the lowly “don’t know”. Trump is stuck where he is. Biden’s up and downs have been at the expense of the “don’t knows”.
Once the final votes come in, there won’t be “don’t know”s anymore. People will vote for one or the other. If Trump’s numbers continue to be stuck in the low 40s, the remainder, Biden’s, will be in the upper 50s, with a 14-20 point vote margin.
This new poll is certainly consistent with this analysis. It shows Trump at 40: at the lower end of his range, but unexceptionally so. At the same time, it shows an unusually low number of undecided voters (3%). With Trump’s numbers staying low, and undecideds approaching zero, it could well reflect what we see on election day.
It is still possible that more undecideds will break for Trump than for Biden. This would raise Trump’s numbers, say to the mid-forties, as the undecideds go to zero, and the Biden-Trumpp margin would tighten. But that is not what we are seeing. 538’s averages are seeing a consistent widening trend, right when early voting is starting and voters are making up their minds.
To summarize, I don’t know if we’ll get a +17 margin, but polls so far suggest to me that a +14 margin or higher in the national vote is likely.