Trump isn't going to lose his voters unless he actually falls asleep during the debate, but Biden a/ IMO doesn't have a base- just people that don't like Trump.
b/ will lose loads of supporters if he does badly.
Biden, IMO, has far more to lose than Trump in the debate. No Trump supporter is going to change to Biden just because Biden doesn't talk to dead people during the debate. Trump supporters will still hate Washington whatever happens.
BTW it's not an good idea to use obviously AI fake photos in your posts.