With President Donald Trump's impeachment as the prize that some Democrats covet -- and others fear -- Robert Mueller will finally sit down on Wednesday for five hours of questioning before two House committees.

The very reluctant witness won't make it easy. So Democrats on the House Judiciary and Intelligence committees have been strategising over how to draw out the former special counsel, who has said he has no intention of going beyond the findings in the 448-page report he completed in March.

"Many Americans, in their busy lives, have not had the opportunity to read the report. It's a pretty dry, prosecutorial product. We want Bob Mueller to bring it to life," Intelligence Committee Chairman Adam Schiff said Sunday on CBS's "Face the Nation."

To best showcase Mueller Intelligence panel Democrats have conducted mock hearings, with a staff member playing the taciturn former FBI director and lawmakers practising how to press him for details in the few minutes each will get, while restraining the urge to grandstand.

"You will find little or no editorializing or speechifying by members -- I hope," said Rep. Jamie Raskin, a Judiciary Committee Democrat from Maryland who predicted "visual aids" will be provided for a national audience watching the testimony on live television.

Mueller investigation: The key figures Show all 12 1 /12 Mueller investigation: The key figures Mueller investigation: The key figures Robert Mueller is the special counsel overseeing the investigation into Russia's meddling in the 2016 election, and potential obstruction of justice by the president. Mr Mueller has a pristine reputation in Washington, where he was previously in charge of the FBI. Throughout his investigation, he and his team have been notoriously tight lipped about what they know and where their investigation has led. REUTERS Mueller investigation: The key figures Former FBI director James Comey was the catalyst that led to the appointment of special counsel Robert Mueller. Mr Comey was fired by the president after Mr Trump reportedly asked him to drop his own Russia investigation. Mr Trump has long maintained that the investigation is a "witch hunt". AFP/Getty Images Mueller investigation: The key figures Deputy attorney general Rod Rosenstein had authority over the special counsel investigation for much of the two years it has been active. Mr Rosenstein found himself with that responsibility after then-attorney general Jeff Sessions recused himself from that oversight. AP Mueller investigation: The key figures Attorney general Jeff Sessions's decision to recuse himself from oversight of the special counsel investigation may have cost him his job in the end. Mr Sessions resigned last year, after weathering a contentious relationship with Donald Trump who vocally criticised his attorney general for taking a step back. Mr Sessions recused himself from the oversight citing longstanding Justice Department rules to not be involved in investigations overseeing campaigns that officials were apart of. AP Mueller investigation: The key figures Attorney General William Barr is currently responsible for oversight of the special counsel investigation. Mr Barr's office will be the first to receive the Mueller report when it is finished. His office will then determine what portion or version of that report should be delivered to Congress, and also made public. EPA Mueller investigation: The key figures Michal Cohn is the president's former personal lawyer, who has been helping the special counsel investigation as a part of a plea deal over financial crimes, and campaign finance crimes, he has pleaded guilty to. Among those crimes, Cohen admitted to facilitating $130,000 in hush money payments to adult film actress Stormy Daniels during the 2016 campaign. Cohen has said he did so at the direction of Mr Trump. Cohen has also admitted that he maintained contacts with Russian officials about a potential Trump real estate project in Moscow for months longer than Mr Trump and others admitted. The talks continued well into 2016 during the campaign, he has said. AP Mueller investigation: The key figures Stormy Daniels has alleged that she had an affair with Donald Trump in 2006, soon after Melania Trump gave birth to Baron Trump. The accusation is of particular importance as a result of the $130,000 hush money payment she received to keep quiet about the affair during the 2016 campaign. AP Mueller investigation: The key figures Paul Manafort was Donald Trump's former campaign chairman. Manafort was charged alongside Rick Gates for a slew of financial crimes, and was convicted on several counts in a Virginia court. He then pleaded guilty to separate charges filed in a Washington court. Manafort has been sentenced to just 7.5 years in prison for his crimes — in spite of recommendations from the special counsel's office for a much harsher sentence. AP Mueller investigation: The key figures George Papadopoulos was one of the first individuals associated with the Trump campaign to be charged by the Mueller probe. He ultimately received a 14 day prison sentence for lying to investigators about contacts he had with Russian officials. AP Mueller investigation: The key figures Roger Stone is a well known political fixer and operative, who has made a name for himself for some dirty tactics. He has been charged by the Mueller probe earlier this year, and he has been said to have had prior knowledge that WikiLeaks planned on publishing stolen emails from the Hillary Clinton campaign in 2016. Getty Images Mueller investigation: The key figures Rick Gates was charged alongside former Trump campaign chairman Paul Manafort for a range of crimes. Gates, who worked alongside Manafort for a pro-Russia Ukrainian political party. The two were charged with conspiracy and financial crimes. Gates pleaded guilty. AP Mueller investigation: The key figures Former national security adviser Michael Flynn was one of the first casualties of the Russia scandal, and was forced out of his position in the White House weeks after Donald Trump took office. Flynn pleaded guilty in 2017 to "willfully" making fraudulent statements about contacts he had with Russian officials including former Russian ambassador to the US Sergey Kislyak. Flynn then lied to Vice President Mike Pence about that contact. REUTERS

Mueller's appearance may be a make-or-break moment for House Democrats to deliver on their promises to investigate Trump and those around him.

Their efforts have been frustrated at every turn so far by the White House's refusal to turn over documents or allow testimony by past and current Trump aides and advisers.

Their ultimate goal is also in question. Judiciary Chairman Jerrold Nadler of New York said this month that "articles of impeachment are under consideration" as part of the committee's investigation. '

'It's very important for the American people to hear directly what the facts are because this is a president who has violated the law six ways from Sunday," Nadler said Sunday on Fox News.

"The administration must be held accountable and no president can be -- can be above the law."

Trump continued to complain loudly about Mueller's public appearance. "Highly conflicted Robert Mueller should not be given another bite at the apple," he said Monday on Twitter.

"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."

But House Speaker Nancy Pelosi has remained firm in her conviction that impeachment by the House would be futile, and politically damaging, unless dramatic new evidence emerges that would lead to the president's removal from office by the Republican-controlled Senate.

"Let's listen. Let's see where the facts take us," she said last week. Suggesting the Mueller testimony risks turning into a political circus, Pelosi added, "And let us have this be as dignified as our Constitution would require."

Robert Mueller is set to face a grilling in Congress, as much of the American public are expected to hear the full details of his report for the first time (Getty Images)

In a division of labour, Democrats on the Judiciary Committee will focus during their panel's three-hour hearing Wednesday morning on Mueller's finding that he couldn't "exonerate" Trump on obstructing justice and the special counsel's seeming hint that Congress ultimately has the constitutional power to make that determination.

According to an official familiar with their plans, Judiciary Democrats will explore specific allegations cited in Mueller's report -- including that Trump ordered then-White House Counsel Don McGahn to have Mueller removed and then to lie about it, that the president ordered former campaign aide Corey Lewandowski to tell Attorney General Jeff Sessions to limit the Russia inquiry to concerns about future elections and that Trump sought to interfere with cooperation by witnesses Paul Manafort and Michael Cohen.

Raskin said he might ask Mueller "why he felt he needed to write letters to protest" Attorney General William Barr's "misstatement of the contents of the report."

For the Intelligence panel's two-hour session on Wednesday afternoon, Democrats plan to concentrate on Mueller's account of contacts between Russians and people involved in Trump's 2016 campaign even though the special counsel said he didn't find sufficient evidence that there was a conspiracy to participate in the Russian effort to help Trump win the presidency.

House Republicans will get almost half the five hours of testimony, and they've indicated that they will play it by ear as to whether to treat Mueller as a friendly witness or an adversary, depending on how narrowly he sticks to the specifics of his report.

Trump disputes top aide's damning Mueller testimony

Some Republican lawmakers have joined in the president's call to investigate whether the Russia inquiry was tainted early on by anti-Trump bias. Others have endorsed Trump's dismissal of the continued Democratic inquiries as a "waste of time."

But Democrats said even a just-the-facts recitation by Mueller will bring alive the findings of a report so thick that few Americans -- including members of Congress -- have really read it. Anti-Trump celebrities have even staged dramatic readings of the report in the effort to focus attention on it.

"Most people don't know what's in his report," said Rep. Jim Himes of Connecticut, a Democrat on the Intelligence panel who favors opening an impeachment inquiry. He said Mueller testifying firsthand could "raise a few eyebrows."