"1986 memo I wrote re: Art of the Deal. Trump couldn't focus for interviews. Can't focus now for debate prep" - Tony Schwartz (who wrote Art of the Deal)
And we all saw through the 3 debates that Trump started off well and then really struggled towards the end e.g.
I'm not disagreeing with you; I'm just asking you to cite one or more of these accounts describing his lack of intellectual stamina.