I fear it won't be as simple as votes, unfortunately. The Transition Integrity Project has been gaming out election scenarios and only one scenario did not lead to civil unrest and chaos, and that was a Biden landslide. Every other one was a clusterfudge. When the incumbent will do anything, literally anything, to stay in power then there are no rules anymore. One side will try and abide by the norms and laws, and the other will kick the board over if they are losing.
You are right in that Barr is the key to all this. They need to impeach him before it is too late, even if a GOP led Senate will not convict. It might take the wind out of his sails if nothing else. And who knows, maybe some repub senators will choose to save their republic at the end.