(CNN) House Democrats are intensely preparing a pointed line of questioning for Robert Mueller, banking that his testimony will shift public perception about the President's alleged criminal activity outlined in the special counsel's report, according to Democratic committee aides.

As part of their strategy, Democrats plan to hone in on five areas of the Mueller report where they think the President clearly obstructed justice, including his efforts to fire the special counsel and to tamper with witnesses like his former campaign chairman Paul Manafort, the aides said.

Democrats also plan to press Mueller on the contacts with Russia and WikiLeaks detailed in the report, in the hopes that Mueller's testimony can combat the President's constant of "no collusion."

The furious work leading up to Mueller's appearance underlines how his testimony is expected to be the most highly anticipated congressional hearing in decades, with the potential to reshape the public narrative and change the House's course on impeachment.

Behind the scenes, preparations are intensifying for both Democrats and Republicans. Four sources familiar with the matter told CNN that Democrats on the Intelligence Committee and Republicans on the Judiciary Committee have already held separate mock hearings with senior aides playing Mueller to help sharpen their questions ahead of Wednesday's back-to-back public hearings before the Judiciary and Intelligence Committees.

Lawmakers are re-reading the Mueller report and watching his past congressional appearances, while committee staff are working to divide up the questions for lawmakers in a way that will be logical to millions of television viewers unlikely to have read the 448-page Mueller report . The Judiciary Committee, which will go first next week, will tackle volume two of the Mueller report on obstruction, while the House Intelligence Committee will follow with questions on Russian election interference detailed in volume one of the report.

Democrats understand they have limited time with Mueller and face major pitfalls, especially if their lines of questioning fall flat or if Mueller fails to provide compelling testimony.

"I don't think Mr. Mueller, based on everything I know about him, that anyone should expect any major departure from the contents of the report," said Rep. David Cicilline, a Rhode Island Democrat on the Judiciary Committee. "I do think the contents of the report are so significant and so damning that when Mr. Mueller brings them to life and actually tells the American people ... it will have an impact."

The committees recognize that Mueller is a reluctant witness, and has stated he does not intend to answer questions beyond the contents of his report. The committee aides said they planned to respect Mueller's desires but noted Congress isn't bound by such limits. The aides anticipate questions will go beyond what's written in the report, such as asking Mueller whether certain episodes detailed would have been crimes had they not involved the President — after Mueller said that his office followed Justice Department legal opinion that a sitting president cannot be indicted

Democrats on both committees are preparing a carefully tailored script to split up questions among their members to try to present a cohesive narrative illuminating the details, though there is nervousness among some Democrats that their colleagues could go off script.

"The risk is not taking full advantage of his time and being able to ask as many questions as possible," said Rep. Raja Krishnamoorthi, an Illinois Democrat on the Intelligence Committee. "I hope it doesn't devolve into a lot of speeches -- that would be a problem."

Committee members say that they are working with the committee to refine their questions, but several noted they ultimately will still be in charge of the limited time they get with Mueller.

Rep. Steve Cohen, a Tennessee Democrat, said he was working with the committee but also had his own questions. "There will be a question or two that will be Steve Cohen and not the team," he said.

Episodes of alleged obstruction

Democratic Judiciary Committee aides say they plan to use their testimony to connect the dots that were laid out in the volume two of the Mueller report, highlighting at least five episodes they feel could have been chargeable obstruction of justice offenses:

Trump's direction to White House counsel Don McGahn to fire the special counsel.

Trump's direction to McGahn to publicly deny that Trump had told him to fire Mueller.

Trump's direction to former campaign manager Corey Lewandowski to tell Attorney General Jeff Sessions to limit the investigation to exclude the President and only focus on future campaigns

Trump's followup direction to Lewandowski to tell Sessions he will fire him if he doesn't meet with Lewandowski

Trump's alleged witness tampering of Paul Manafort, Michael Cohen and others, including encouraging them not to cooperate, dangling pardons and congratulating Manafort for not flipping.

House Intelligence Committee aides, meanwhile, say they plan to focus on the contacts with Russians and WikiLeaks highlighted in volume one of the report, including Trump's knowledge of the WikiLeaks' email dump ahead of time and the President's touting of the stolen emails more than 100 times.

Their task is complicated by the fact that the section on Russian election interference is more complex, and some of the material is redacted, which is why that panel was pushing for a closed session with Mueller's deputies where they could discuss classified information.

"A lot of attitudes have hardened on the subject of Trump and Russia and obstruction of justice, but nonetheless, if there's anyone who can cast a new light on this issue, it's the man who did the investigation and probably holds unique credibility with the public," said House Intelligence Chairman Adam Schiff.

The California Democrat added: "Up until now, they've only had the Mueller report filtered through people like (Attorney General) Bill Barr, who misrepresented it. So it's going to be vitally important for the public to hear from Mueller about how the Russians systematically interfered in our election, how the Trump campaign welcomed it, made use of it, and then lied about it to cover it up. That's all very powerful."

Trump has claimed vindication from the Mueller report, frequently saying and tweeting: "no collusion, no obstruction."

Mueller's report did not establish a criminal conspiracy between Trump's campaign and the Russian government, but the special counsel said he could not exonerate Trump on the question of obstruction of justice. Trump and his allies, however, have pointed to Barr's decision not to charge on obstruction.

Republicans conducting their own preparations

Republicans are also meticulously preparing for the Mueller hearing, which gives the special counsel's most vocal critics their chance to press Mueller about their allegations involving anti-Trump text messages exchanged by members of his team and the use of a surveillance warrant that was obtained on a Trump adviser.

"I think there are a lot of questions about the team," said Rep. Mike Conaway, the Texas Republican who led the House Intelligence Committee's Russia investigation, referring to the special counsel's team.

Georgia Rep. Doug Collins, the top Republican on the Judiciary Committee, said his members are prepared to address the topics they want to cover, but he argued the pressure was on the Democrats to deliver next week.

"At this point I think the expectations are entirely on the Democrats," Collins said. "The hype is on the Democrats to find out something new out of a well-read report that again, at the end of the day, Mr. Mueller has done all he's going to do."

But Republicans are still making sure they'll be ready. Rep. Matt Gaetz, a Florida Republican on the Judiciary Committee, said he has watched hours of Mueller's previous congressional testimony in preparation for the hearing.

"Mueller is the LeBron James of using 300 words to say absolutely nothing," Gaetz said.

Rep. Devin Nunes, the top Republican on the Intelligence Committee, has not commented to CNN and others about the Mueller report. But he told Fox News' Sean Hannity this week that he would try to prevent Mueller from trying to "embellish."

"When it comes to Republicans asking questions, I think what we need to do is stick to the facts of the case and not allow Mueller time to either pontificate and embellish all the time or embellish things that he may want to embellish," Nunes said. "This investigation was not about collusion. It wasn't about obstruction of justice. It was about setting obstruction of justice traps so for the better part of two years they were hoping the President would fall into it."

A reluctant witness

For weeks, members on the House Judiciary Committee have been engaged in tense discussions over whether to launch an impeachment inquiry -- and the junior members of the committee had been angry that they initially had been shut out from asking questions under the previous agreement with time limits for Mueller's testimony.

But after Nadler helped resolve that concern by delaying the hearing for a week so Mueller would testify an hour longer to allow all members to ask questions, although aides would not commit Wednesday that everyone would get a full five minutes. Judiciary Committee Democrats met for a dinner hosted by Pennsylvania Democratic Rep. Mary Gay Scanlon on Wednesday evening for an informal discussion about their momentous week ahead.

Aides and lawmakers said studying Mueller's previous testimony was just one of the ways they're preparing for next week's hearing. They've workshopped possible questions with committee staff and one another, and honed their questions at mock hearing sessions, where the Intelligence Committee's director of investigations Daniel Goldman and the Judiciary Committee's minority chief oversight counsel Carlton Davis each played the role of Mueller.

Those sessions are likely to continue next week up to the hearing.

"I've been involved in 100 hearings, and we've never prepared for one the way we have prepared for this one," said one Judiciary Committee aide.

Mueller's long government career has given the two committees plenty of material to study from Mueller's past congressional appearances. The bottom line is they don't expect Mueller to readily volunteer information, aides say, particularly given that he doesn't want to testify before Congress.

But Democrats say that even if Mueller just reads the report to the public, it has the potential to make a significant difference, given that most of the public hasn't read the report and they feel Barr and Trump have misrepresented its findings, coloring the initial public perception.

Those backing an impeachment inquiry point to the impact that Mueller's June statement had to convince dozens of Democrats to join their effort, and they anticipate that will only intensify once he appears next week.

Florida Democratic Rep. Ted Deutch said Democrats' strategy for the Mueller hearing should be a simple one: "We should let him speak for himself."

CORRECTION: This story has been corrected to more accurately describe a meeting Democratic lawmakers had Wednesday to prepare for the Mueller hearing.