How? What do you use to get him to change his mind?
He has money. I doubt there is anything in his closet to be used as leverage. He is likely too self centered that an appeal "for the good of the nation" or party would sway him.
He is exactly where he has spent his entire life trying to be and I think he honestly believes he is doing a great job.
Those in cognitive decline don't think they are having an issue. That is why you have to hide Grandma's keys. She thinks she can drive just fine.
He said the only way he would step aside is if God told him to. I don't think he meant Obama.