President Trump Donald John TrumpSteele Dossier sub-source was subject of FBI counterintelligence probe Pelosi slams Trump executive order on pre-existing conditions: It 'isn't worth the paper it's signed on' Trump 'no longer angry' at Romney because of Supreme Court stance MORE's personal attorney Rudy Giuliani Rudy GiulianiThe Hill's Campaign Report: GOP set to ask SCOTUS to limit mail-in voting CIA found Putin 'probably directing' campaign against Biden: report Democrats fear Russia interference could spoil bid to retake Senate MORE said he doesn’t expect former special counsel Robert Mueller Robert (Bob) MuellerCNN's Toobin warns McCabe is in 'perilous condition' with emboldened Trump CNN anchor rips Trump over Stone while evoking Clinton-Lynch tarmac meeting The Hill's 12:30 Report: New Hampshire fallout MORE to stray from his Russia report during Wednesday's congressional testimony, adding that anything new would be "highly questionable."

“I can’t imagine he’s going to say anything that we don’t know,” Giuliani said during an interview that aired Monday. “If he does, it would be highly questionable — how come you’re saying it now and you didn’t say it in the report.”

“And number two: It would be totally unethical,” Giuliani added. “If a prosecutor doesn’t bring a case, then the prosecutor’s got to keep his mouth shut about the facts because it is so unfair to the person who after all isn't going to be charged.”

Mueller is scheduled to appear Wednesday before the the House Judiciary and Intelligence committees to testify about his two-year probe.

Giuliani argued last week that he doesn’t think Mueller should testify, saying “it’s not proper.”

Mueller has made clear he doesn’t intend to go beyond the findings of his report, which found no evidence of conspiracy between the Trump campaign and Russia but also did not reach a judgment on obstruction of justice regarding Trump.

In his 448-page report, Mueller detailed 10 episodes that were examined for possible obstruction. Mueller later said that he could not bring charges against Trump, citing Justice Department guidelines against indicting a sitting president.

While Democrats plan to use the public testimony to ramp up their investigations into Trump, with some hoping it will move the needle impeachment efforts, some Republicans and Trump have sought to discredit Mueller.

“Highly conflicted Robert Mueller should not be given another bite at the apple,” Trump tweeted on Monday. “In the end it will be bad for him and the phony Democrats in Congress who have done nothing but waste time on this ridiculous Witch Hunt.”

Trump also said he might watch part of the Mueller testimony after previously stating that he would not.

—Tess Bonn