There's your problem. I would never talk to a demoncrat; much less allow one into my home.
The problem is that Democrats don’t respect us and have been unwilling to work with Republicans for the last 30 years. I would suggest that you respond by letting him know that you cannot be friends any longer. To do so is to give implicit approval of his feelings and his politics. I have made a commitment to avoid and denounce anyone I know who had voted for Biden...and that includes my favorite Uncle Stan and several neighbors around me.