A comment from a solid Trump supporting friend:
"The problem was the President had two opponents, Biden and the moderator".
I agree because Biden is currently in the lead. Trump knows it and it is highlighted by the fact that in the last segment, all that Biden is pushing is to vote while Trump is spinning conspiracy theories about election fairness to the point of saying that the FBI director who he appointed was wrong.
That's what I would have liked to see Biden do more. Trump claims he is the best and so are his people. Why are they wrong and why has he fired more of them than any other president? Trump went on about forest management in California. Most of the forested land there is federal and Biden didn't even say a peep about it.
The reality is that Biden supporters and moderate will be turned off by the boorish behavior and Trump supporters and moderates will be disappointed by Biden's hesitant demeanor. As many have said and I agree, this debate will not incite any supporters to change their mind and I doubt that the roughly 10% of undecided voter would be any clearer now.