Gonna keep repeating this point, because it has a variety of implications for vote counting, what happens if some ballots come in after the deadline, etc.: There is lots of evidence that Democrats sent their ballots in sooner than Republicans.

In Florida, for example, mail ballots received by the morning of Oct. 14 were +21 D by party registration. But ballots received in the past 48 hours were just +6 D.

Particularly if Ds with outstanding mail ballots are hearing messages from the Biden campaign etc. and are also now more likely to use dropboxes, or to decide to vote in person instead, it's not clear what the partisan composition of late-arriving mail ballots will look like.