It is at times like this that you are reminded that Trump isn't a skilled politician in any way, shape or form. He's just a demagogue who has tapped into a particularly rich vein of populism. Admittedly that has taken a degree of organisation and ability from those around him, but he is fundamentally one dimensional, both on a personal and political level.
Kamala Harris, by contrast, has shown more political skill and judgement in the past couple of months than I had expected from what I had seen of her in recent years. She is far from a perfect candidate. Few politicians are. But politics is a skill, and her tactics in the debate were absolutely spot on and deflected from her own weaknesses whilst exploiting Trump's. It was pretty clever stuff. In the moment he no doubt thought he was responding in a perfectly persuasive manner, but he absolutely wasn't, and I don't think there's any real prospect of him performing better in a second debate because he simply isn't going to listen to those around him to the extent that he can compensate for his very real personality flaws.
What has happened since just writes itself. Of course he's going to decline a second debate. Of course she's going to ask for one, and say that the people deserve one. He is cutting his losses and she uses that to take the high ground. I don't see how he could really do anything else. Well, he could not spread the whole story about people eating dogs, but let's not expect too much of him.
There is, of course, still a long way to go. Politics is a fickle game and a lot can happen between now and November. This is also a far more finely balanced election than it has any right to be, even at this stage. But for now, Harris is doing well and is the slight favourite.