Robert Mueller will air "very substantial evidence" of wrongdoing by Donald Trump and make a public case for impeachment when he appears before congressional hearings this week, it has been claimed.

The lawyer’s investigation into Russian interference in the 2016 election shows the US president is guilty of "high crimes and misdemeanours", says Jerrold Nadler, the House Judiciary Committee chairman.

"This is a president who has violated the law six ways from Sunday," the leading Democrat said. "We have to present, or let Mueller present, those facts to the American people...because the administration must be held accountable and no president can be above the law."

Mr Mueller will answer questions about his findings – which specifically looked at links between the Russian state and Mr Trump’s election campaign – during back-to-back hearings on Wednesday.

Analysts suggest his testimony could be pivotal in shifting public opinion on if the president should be held accountable for those apparent links.

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

The report itself – a redacted version of which was published in April – did not find sufficient evidence to establish charges of criminal conspiracy. But it did suggest Mr Trump may have tried to obstruct the investigation.

Now Democrats on the Judiciary Committee have said they plan to focus on a set of episodes laid out in the report to direct the attention of Americans to what they see as the most egregious examples of the president's conduct, which point to obstruction of justice.

Those examples include Mr Trump's directions to then-White House counsel Donald McGahn to have Mr Mueller removed and, later, orders from Mr Trump to Mr McGahn to deny that happened.

Democrats also will focus questioning on a series of meetings Mr Trump had with former campaign manager Corey Lewandowski in which the president directed Mr Lewandowski to persuade then-Attorney General Jeff Sessions to limit Mr Mueller's investigation.

But Doug Collins, the top Republican on the committee, argued that "any thought of impeachment is waning" and that the American public has moved on.

He added that Republicans will be focused in their questioning on making clear that the Mueller report represents a "final episode" in the Russia probe, which he described as flawed.

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