Republicans are preparing an aggressive defense of President Trump surrounding former Special Counsel Robert Mueller’s congressional testimony Wednesday, with the president's campaign and the party firing up a war room meant to highlight "Democrat hypocrisy" -- and GOP lawmakers poised to use the hearing to scrutinize the origins of the Russia probe itself.

Mueller is set to appear Wednesday before the House Judiciary Committee and the House Intelligence Committee for back-to-back public hearings. As Democrats plan to use the forum to spotlight allegations against Trump of obstruction of justice, Republicans are homing in on questions about the early stages of the investigation that eventually was overtaken by Mueller.

DOJ TELLS MUELLER HIS TESTIMONY 'MUST REMAIN WITHIN THE BOUNDARIES' OF PUBLIC REPORT

On the sidelines will be a political operation that rivals the counter-messaging from Republicans during Democratic presidential primary debates. This week, the Trump campaign and Republican National Committee are working together on a “multi-day bracketing effort” involving a rapid response team and full social media and digital presence.

“House Democrats are hell-bent on spending more time on this witch hunt and we’re going to aggressively call them out for their political games,” Trump Victory Regional Director Rick Gorka told Fox News. “This is going to highlight the Democrat hypocrisy and will hold them accountable for their latest photo op.”

Gorka told Fox News that the joint effort will also include a team of people to clip “poignant” moments during the hearing. Gorka said a “booking operation” will make Trump surrogates available for television and radio interviews before, during and after Mueller’s testimony.

“We’ll call the Democrats out on their delusion and then showcase what they should actually be focused on,” Gorka said, pointing to other top administration agenda items like border security and the United States-Mexico-Canada Agreement (USMCA). “Democrats have done nothing but peddle baseless investigations at a great expense to the American taxpayers instead of tackling the issues Americans have told us are a priority to them.”

He added: “The report was clear. No obstruction. No collusion. This is Democrats just being willing to say and do anything to keep this thing alive. They are so invested in this narrative.”

While Mueller did not find evidence of a criminal conspiracy between the Trump campaign and Russia, he did not reach a conclusion on whether the president obstructed justice.

Meanwhile, on Capitol Hill, Republicans on both committees plan to focus their questions on the origins of the Russia investigation—including questions on Foreign Intelligence Surveillance Act (FISA) warrants against the Trump campaign in 2016, the unverified anti-Trump dossier, and evidence of political bias from special counsel team members like former FBI officials Peter Strzok and Lisa Page.

One Republican source told Fox News they expect Mueller “to try to get out of answering a lot of those questions,” claiming they are “outside the bounds” of his report—specifically on the issue of how the FBI could have used the dossier to obtain FISA warrants. The source said he may also say that “those questions are subject to ongoing investigation.”

The Justice Department told Mueller that his testimony “must remain within the boundaries” of the public, redacted version of his report, according to a letter obtained by Fox News.

TRUMP SAYS MUELLER SHOULDN'T TESTIFY, WARNS HEARING WILL BACKFIRE

“We’re not expecting him to be forthcoming with answers on that stuff, one way or another,” the source told Fox News.

At the White House, Trump has attempted to discredit Mueller by calling him “highly conflicted,” suggesting he should not be given the chance to testify.

“Highly conflicted Robert Mueller should not be given another bite at the apple. 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 tweeted Monday. “Result of the Mueller Report, NO COLLUSION, NO OBSTRUCTION.”

Trump also proposed that certain questions be asked of Mueller—about the FBI’s handling of the investigation into Hillary Clinton’s use of a private email server and handling of classified information while secretary of state and about anti-Trump text messages exchanged between Strzok and Page, who were romantically involved.

The president and congressional Republicans have been asking questions about Strzok and Page, and how the Russia investigation began, for months. Attorney General Bill Barr appointed U.S. Attorney from Connecticut John Durham to examine the backstory, including all intelligence collection activities related to the Trump campaign during the 2016 presidential election, alleged misconduct and alleged improper government surveillance.

But House Judiciary Committee Chairman Jerrold Nadler, D-N.Y., said he isn’t worried about Republicans asking questions of Mueller about the origins of the probe, and claimed they would only be wasting their time.

"It's been very clear that the Trump investigation was not predicated on the so-called dossier that they're talking about. There was nothing wrong with the FISA application. All the things they're talking about have been gone through. The inspector general found that there was nothing wrong with the other half of what they’re talking about, which is the Hillary [Clinton] investigation. He's finishing it," Nadler said on “Fox News Sunday.”

"If they want to debate, or discuss, I should say, this irrelevancy, let them waste the time,” he continued. “But what's before the American people now is the conduct of this president. And what Mueller found about the conduct of this president and where we go from here."

Mueller only spoke in public about his investigation once. In May, Mueller hosted a press conference (he did not take any questions) outlining his findings, noting there “was not sufficient evidence to charge a conspiracy” over whether members of the Trump campaign coordinated with the Russian government during the 2016 presidential election. His language on the question of whether the president obstructed justice, though, left the issue open—a move that Democrats took as a signal to ramp up their investigations.

Meanwhile, Fox News learned last week that Democrats on the Judiciary and Intelligence Committees are expected to focus their questioning on five areas in Mueller’s report having to do with his inquiry on “obstruction,” rather than on accusations of the Trump campaign colluding with the Russians, in an attempt to expose potential wrongdoing by the president.

Among the topics they are expected to focus on: Trump’s reported call to then-White House Counsel Don McGahn to remove Mueller; the claim the president ordered McGahn to deny he told him to try to get rid of Mueller; allegations the president told former campaign manager Corey Lewandowski to instruct then-Attorney General Jeff Sessions to curb the probe; the dangling of pardons to former campaign manager Paul Manafort; and allegations of witness tampering, including with Manafort.

Democrats have prepared a six-page strategy document ahead of the hearing. The document quotes directly from Mueller's report and focuses on securing and defending elections, preventing foreign interference and influence, and ending abuse of power.

"Our Democratic House Majority will continue to fight for our national security by securing our elections, safeguarding our democracy and holding the President accountable – because no one is above the law," the document says.

Nadler and House Intelligence Committee Chairman Adam Schiff, D-Calif., subpoenaed the former special counsel to testify after Mueller expressed his reluctance to appear before Congress for questioning.

Fox News' Chad Pergram and Jake Gibson contributed to this report.