If you go by Trump's popularity ratings since being elected, there's relatively few people who seem to migrate, which I attribute largely to the apparent absence of any objective media reporting whatsoever in the US. The Trumpers watch Fox and get constantly hammered with the message of how great he is, whereas the non-Trumpers watch CNN/NBC, etc.., and get constantly hammered with the opposite message. After four years of that, none of them will change their minds (with the slight caveat that Fox has occasionally started being more critical of Trump lately, though I think not enough to undo the effect of the last four years of constant cheerleading).

I think the critical thing will be turnout and which side can get more people to go and vote and/or whether the Rs can effectively disenfranchise enough D voters.

As for turnout, Hillary was completely uninspiring and it should be easy for Biden to outperform her caveat emptor. The problem is the pandemic and all the mail in voting shenanigans it opens the doors to, which Trump will try to exploit as much as possible.

And wow, lol that the Ds are just as corrupt as Trump. I don't know what planet you have to live on to believe that. Even the Rs aren't as corrupt as Trump.