The quote:
“Given Joe Biden’s incredible record, given Donald Trump’s terrible record: he should be mopping the floor with Donald Trump. Joe Biden is running against a criminal. It should not be even close. And there is only one reason it is close. And that is the president’s age.”
I think it’s simultaneously less conspiratorial and more nefarious than that: the establishment wing of the party likes power and power means control over campaign funding, so they pander to large corporate donors by suppressing anti-corporate populists.