The whistleblower, the ICIG will be called as witnesses; and, the deposition of the ICIG will subpoenaed.
This is war, and these Congressmen know what questions need to be asked. Democrats must be scared to death.
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 purvey 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.
The first witness for the defense should be Michael Atkinson, the Inspector General who handled the "whistleblower" complaint. There's a reason why Schiff has adamantly refused to release the transcript of Atkinson's testimony in Schiff's secret committee proceedings last fall.
Perhaps the second witness should be Mark Zaid, the attorney who allegedly represents this "whistleblower" (along with other individuals related to Schiff's farce). He's also the one who posted that Twitter message back in 2017 where he bragged that many individuals were going to engage in a "resistance" against President Trump with the intention of pushing him out of office. Zaid would have to testify very carefully. He does not have to testify to any privileged matters related to his clients (at least not right away), but in order to assert this privilege he will first have to identify WHO HIS CLIENTS ARE.
I suspect the case brought by Schiff and Nadler will be in shambles long before Trump's team even gets to the whistleblower.
Yes, the should know what questions to ask, but will they ask them? Will they actually subpoena every from Schiff to Nadler, to Clinton and Obama, and McCabe, etc. Plus the “whistleblower”? And, of course, both Joe and son?