I'm not sure how heavily you weigh this because I believe you talk like you're going to stay in until it becomes hopeless. Very few people in history have given up power gracefully, that's just the nature of power.
Here is what Biden told the campaign call, according to a Politico reporter:
"Let me say this as clearly as I possibly can as simply and straightforward as I can: I am running…no one’s pushing me out. I’m not leaving. I’m in this race to the end and we’re going to win.”
I think it's awfully telling that Republicans and Trump have stopped calling on Biden to step down. They know they will crush him if he stays in the race because there is no recovering from that debate.