There's only one small problem with that: Who is the "whistleblower?"
Before you say "Eric Ciaramella," remember that in a legal proceeding, there is a huge danger in making assumptions about facts that are not established in the record of the proceedings at hand. And to the best of my knowledge, this so-called "whistleblower" has not been publicly identified anywhere except in media accounts -- many of them from half-baked conservative news websites that peddle fake news as badly as CNN does.
Before calling the "whistleblower," the defense team must first establish who exactly he is. That means they must first get their hands on all the records related to this person and his dealings with Schiff's staff. Personally, I suspect that either their is NO whistleblower, or there may be at least a half-dozen people who provided information to Schiff's staff in a way that they might be considered "whistleblowers" of one kind or another.
Or they could simply interview people behind the scenes having knowledge of events, including Ciaramella, such that whatever he says to investigators is under oath.
Not singling him out, but including him.
Josh Hawley is on FNC saying they should call both Biden’s, the Whistleblower and Schitt.
The Whistleblower could already have been heard from, but we don’t realize who it is. I nominate Vidmsn.