If all the Independents are siding with Biden, which seems to be the way it’s going, of course his enthusiasm is lower on average.
Independents are always being given a choice between two things, neither of which they really like. In this case, the fact that ALL of them plan to vote for Biden means he will win the election handily.
Then why are they addressing a non issue?
Independents do not yet know that Biden is senile since the DNC and the mass media have been hiding him in the basement.
They will get an introduction to the “new” Joe Biden, courtesy of the Trump campaign, in October.
When the ad campaign is over, the former low information independent Biden supporters will be terrified that he will accidentally cause a nuclear war because he is senile.
That will be the message, and it will be a powerful one...