The Bidens have NOTHING to do with the impeachment accusations. Nothing at all.
Unless they were a partner in Ukraine corruption. But then, only an investigation could determine if the Biden's were guilty or innocent. What are they afraid of? If they were both innocent, an investigation would prove that and Trump not only would look like a fool, but give a boost to the Biden campaign. But, all I hear is, we should not investigate American citizens for their activities in foreign countries. Especially if they are politically connected or running for office.
I, for one, believe, if they are broken the law or are innocent, it should be found out before they are elected, not after.