Fundamentally, the "fundamentals" are improving for Trump.

* The economy is getting better, although that could be threatened by Congressional inaction.

* COVID cases are going down, although that could reverse itself at pretty much any time.

* The protests are getting less coverage than they were before, and public opinion about them is becoming less sympathetic.

All of these are reasons to think the race could tighten.

There are some counterarguments too. Even if COVID cases are decreasing, the downstream consequences (i.e. disruption to schools) are still piling up and will likely continue to do so thru November. The Post Office could be a big negative story for Trump.

Still, it's not hard to envision the race tightening, and indeed the 538 model did expect the race to tighten somewhat, which is one reason why it has continued to give Trump much better odds than other models.