Former congressman Trey Gowdy previewed potential questioning for former Special Counsel Robert Mueller ahead of his long-awaited Wednesday testimony.

"Mueller found some things, you can go there. He didn't find some things, you can go there. He didn't bother to look for certain things, you can go there and then you have the issue of the bias within the investigation," Gowdy said on "Hannity" Tuesday.

JUSTICE DEPARTMENT TELLS MUELLER HIS HOUSE TESTIMONY 'MUST REMAIN WITHIN THE BOUNDARIES' OF PUBLIC REPORT

"Then you have another category, legal issues. It's interesting to me whether or not you can even obstruct an unpredicted investigation you can certainly resist an unlawful arrest."

"So those are five tranches but you've got to be prepared and I'm sure both sides will be for tomorrow," Gowdy added.

Gowdy warned that it was unlikely America would learn anything new from Wednesday's hearings.

He's not going to deviate from the report for two reasons quite frankly. Number one: Prosecutors are not supposed to deviate from their charging decision or noncharging," Gowdy said.

"Let's assume he does say something new or different tomorrow your follow up question is going to be 'what the hell was that not your report?'"

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The former congressman advised those questioning Mueller to stick to "things he did not bother to look for."

"I would spend almost all of my time asking him on panel about things he did not bother to look for such as the origin of this investigation in June of 2016," Gowdy told host Sean Hannity.