Bolton should be a fact witness. Hunter Biden never could be in this case.
Really? We should not ask Biden why he was working for and paid by the most corrupt company in Ukraine? It goes to the heart of why Trump asked Zelinsky to investigate. In addition, Alexandra Chalupa and the 'whistle blower' should also testify.
But, I would guess you would not want to hear from them. Only those that could hurt Trump feed your appetite for witnesses.