My hunch is that Biden will refuse.
Biden doesn't decide to do,or not do,anything.
He is a "Flesh Puppet" that has been trained to parrot words without even having a clue as to what they mean.
From what I understand,he was NEVER very bright,but in the last few years he has added severe senility to natural stupidity,and there ain't no coming back from that.
He is NOT going to debate anyone,period. If he pretends to do so,it will be someone "in on the deal/steal" who is willing to allow Biden to have a receiver in his ear so someone can remind him of the correct answers to any question and tell him what to say when he forgets.
And the worse part about it is that everybody in Congress and the US Senate know this,and nobody is talking about it in public. I have more contempt for them than I do Biden.