We've conducted four polls of Wisconsin over the last year, and we can go back and join them up to some of the absentee voting data there. It's a little out of date, but the folks who have already voted, per our data, backed Biden... 82-18 among decided major party voters.

It's potentially pretty useful data. Wisconsin is not a state with party registration or partisan primary vote, so all of this lopsided mail voting does make it easier to identify Democrats and Republicans... though doing so does come with risks.

The risk, interestingly, is that using this data could hurt Democrats in a Wisconsin poll.
In general, partisans are most likely to respond to surveys. Here, we have a great way to see Dems!
But we don't quite have a similar way to see Republicans, so they might remain too high

Hilariously one of our better ways to 'see' Republicans is whether you voted in the August 2012 primary. A real barnburner on the GOP side lol
https://en.wikipedia.org/wiki/2012_United_States_Senate_election_in_Wisconsin

Because nearly as many Democrats voted as Republicans, so it's not very useful. Honestly, based on our data, I'd guess the 2016 primary electorate in WI voted Clinton, even though D>R ballot, with so many college grad GOPers voting Clinton later https://twitter.com/rd_aloe/status/1320132090504093696?s=20

A lot of people are asking about TargetSmart modeling, which shows a tight race in partisan balloting.
The problem, as I've alluded to already in this thread, is that there's not really any good data (until mail voting lol) for identifying partisans in Wisconsin

Our voter file vendor (L2) classified these Biden 82, Trump 18 respondents as Dem 42, GOP 37.
I'm not trying to be critical of either firm; there's just not much you can do to reliably identify partisan voters in a state without partisan data and limited geo/demo polarization

We've slowly been building up our own models in these states as we collect more data. Back in our first poll of WI-1 in '18, before we ever had any WI data, you can see how mediocre they were

And no one should be surprised by a wide Dem mail ballot edge in WI. It's the same story as Pennsylvania, except you know it there because of there's party registration.