House Democrats, concerned president Donald Trump‘s attorney general may withhold evidence of wrongdoing uncovered by special counsel Robert Mueller, are preparing for potential battle over access to the full contents of Mr Mueller’s newly completed report, vowing to pursue it and any underlying investigative materials in court if necessary.

“We will fight” for the full report, said representative Jerrold Nadler, chairman of the House Judiciary Committee, emphasising that Democrats expect complete transparency from Mr Mueller and the Justice Department, save for redactions of classified information that could jeopardise sensitive law enforcement methods if disclosed publicly.

Attorney general William Barr informed the heads of the House and Senate Judiciary Committees in a letter on Friday he might be able to advise them of Mr Mueller’s “principal conclusions as soon as this weekend”.

He also noted neither Mr Barr nor his predecessors had challenged any actions Mr Mueller took during his probe.

But with limited power to compel information from potential witnesses, congressional Democrats are looking to Mr Mueller’s findings to inform their investigations of Mr Trump’s campaign, businesses and alleged foreign ties – and insist they will be satisfied with nothing short of a complete account of the results and the evidence that informed them.

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 special counsel’s investigation focused on questions that go to the integrity of our democracy itself: whether foreign powers corruptly interfered in our elections, and whether unlawful means were used to hinder that investigation,” house speaker Nancy Pelosi and senate minority leader Charles Schumer said in a joint statement after Mr Barr announced Mr Mueller had completed his report. “The American people have a right to the truth. The watchword is transparency.”

The stakes are high: If the special counsel found evidence Mr Trump committed a crime, participated in a cover up, or otherwise engaged in conduct undermining the public trust, it could fuel calls for impeachment, which Democratic leaders have resisted absent proof of wrongdoing.

According to the Justice Department, Mr Mueller has not recommended any further indictments – news Mr Trump’s defenders in the GOP took as vindication.

“The reports that there will be no new indictments confirm what we’ve known all along: there was never any collusion with Russia,” representative Steve Scalise of Louisiana, the House’s second-ranking Republican, said in a statement.

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Mr Trump’s disdain for Mr Mueller’s probe, which he has labelled a “witch hunt”, and his animus towards congressional oversight, which he considers “presidential harassment”, have fed Democrats’ suspicion he might have something to hide and might attempt to force Mr Barr to conceal any unsavoury details from public view.

As a result, Ms Pelosi and Mr Schumer warned on Friday it was “imperative” Mr Barr publicise Mr Mueller’s findings no later than the president was made aware of the report’s contents.

“Attorney general Barr must not give President Trump, his lawyers or his staff any ‘sneak preview’ of special counsel Mueller’s findings or evidence,” they said. “The White House must not be allowed to interfere in decisions about what parts of those findings or evidence are made public.”

Republicans say the full report should be released. But they have stopped short of echoing the Democrats’ concerns, expressing faith Mr Barr will be as transparent as possible – indicating they will defer to Mr Barr, not fight him.

“We’re jumping about 60 steps too far,” said the Judiciary Committee’s ranking minority-party member, representative Douglas Collins when asked about the Democrats’ plans. “At this point in time I’m not going to question my attorney general’s veracity or the fact that he’s going to do what he says he’s going to do. Until he proves me wrong.”

Criminals who worked for Trump Show all 5 1 /5 Criminals who worked for Trump Criminals who worked for Trump Michael Cohen Former lawyer for Donald Trump was sentenced to three years in prison on counts involving evading income tax, false disclosure of the hush money paid to Stormy Daniels and another hush money charge Getty Criminals who worked for Trump Paul Manafort Former campaign manager for Trump Manafort was found guilty in February 2018 of five counts of tax fraud, two counts of bank fraud and one count of failure to disclose a foreign bank account. The crimes occurred prior to his appointment in Trump's campaign Getty Criminals who worked for Trump George Papadopoulos Former Trump campaign adviser Papadopoulos pleaded guilty to lying to the FBI in October 2017. He had lied about making contact with a professor who claimed that the Russians had dirt on Hillary Clinton. He was sentenced to 14 days in jail Getty Criminals who worked for Trump Michael Flynn Former White House National Security adviser Michael Flynn pleaded guilty to lying to the FBI in December 2017. He had lied about conversations that he had with the Russian ambassador to the US during Trump's Presidential campaign. He was not given prison time due to his "significant assistance" to the Mueller investigation Getty Criminals who worked for Trump Rick Gates Deputy chairman of Trump's presidential campaign Gates pleaded guilty to lying to the FBI in February 2018 AFP/Getty

Regulations governing Mr Mueller’s work, which centres on Russia’s interference in the 2016 presidential election and whether anyone in the Trump campaign conspired with those efforts, require the special counsel only to provide Mr Barr with a confidential report explaining why he elected to prosecute certain individuals or declined to do so.

Mr Barr may release the report publicly, if he deems it “in the public interest.” That is not required, though he is under considerable pressure to do so.

One key question Democrats have is whether Mr Mueller has concluded that Mr Trump engaged in criminal activities but declined to charge him in deference to Justice Department policy that a sitting president may not be indicted. Such information should be made public, they argue.

“If the special counsel has reason to believe that the president has engaged in criminal or other serious misconduct, then the Justice Department has an obligation not to conceal such information,” the Democratic chairs of the six House panels conducting investigations that dovetail with Mr Mueller’s probe said in a joint statement Friday night. “Anything less than full transparency would raise serious questions about whether the Department of Justice policy is being used as a pretext for a cover up of misconduct.”

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Compounding Democrats’ unease are remarks made in February by deputy attorney general Rod Rosenstein, who said the Justice Department should not reveal information about people it does not charge with crimes.

That suggests the department will not release interviews, emails or other material concerning the president and others who were not charged, even though such information could be useful to ongoing investigations in the House.

“I’m concerned that [DOJ is] signalling they’re going to fight the Congress when it comes to [Mr Mueller’s] underlying evidence,” said representative Adam Schiff who as chairman of the House Intelligence Committee is leading one of six Trump-related probes in the House.

The Senate Intelligence Committee is also examining Russia’s activities surrounding the 2016 election, a probe that began shortly after Mr Trump’s inauguration.

“We’re going to have to pick and choose our legal battles,” Mr Schiff added, but “it seems to me there are few fights as important as this one”.

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To obtain the full report, Democrats will likely first negotiate with the Justice Department. An offer to let members read it in a secure room designed for viewing classified materials would not suffice, Mr Nadler said.

“No, no, no,” he said. “Information that goes to [intelligence] sources and methods should not be public. But everything else should be.”

If negotiations fail to produce the complete report and its underlying evidence, then the Democrats will move to more coercive measures such as subpoenas, Mr Nadler said. “The next step after that is to ask Mueller to testify in front of the committee,” he said.

If the Justice Department resists, Ms Pelosi would have to decide whether to start a political battle by seeking to hold administration officials in contempt of Congress – a decision likely to result in lengthy court fights. The administration could also seek to prevent disclosure of material involving the president by claiming it is subject to executive privilege, but such claims are not absolute.

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Mr Nadler and Mr Barr met in March for a working lunch, their first face-to-face meeting. Mr Nadler said he conveyed the importance of releasing the full report and underlying materials. Mr Barr, he added, “just repeated that he’d do what he could and wanted to have as much disclosure as possible, period. He wasn’t getting specific and couldn’t get specific.”

Mr Nadler cited two instances in which a court found that the executive branch could turn over grand jury material, one during the congressional investigation and impeachment proceedings of president Richard Nixon and the other during the 2010 impeachment trial of Thomas Porteous, a federal judge from Louisiana who was accused of taking bribes from lawyers and lying to lawmakers during their investigation.

“It should not be necessary that there be a formal impeachment proceeding for Congress to get that material,” Mr Schiff said. “It should be enough that Congress has a public purpose for it.”

Mr Nadler said it’s important for the public to see the full report, whether it implicates or exonerates the president, to begin to restore trust in government. “The reason Mueller was appointed in the first place is there’s a crisis of confidence,” he said. “To the extent he knows something or reaches a conclusion, the public ought to know it, and ought to know the underlying evidence.”

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The Democrats intend to leverage a precedent set by the Justice Department during the last Congress in connection with Republican-led investigations into Hillary Clinton’s use of a private email server, the dismissal of FBI deputy director Andrew McCabe and allegations of bias among law enforcement officials involved in the Russia investigation. In those matters, the department released to Congress hundreds of thousands of internal documents regarding the FBI’s decision-making, and all underlying documents involving the surveillance of a former Trump campaign official.

Though he warned against the practice then, Mr Schiff said he believes the department should match or outpace that level of compliance with regard to Mr Mueller’s work, to avoid the “appearance of being orchestrated” by the president.

The chairs of the six House panels investigating Mr Trump, including Oversight, Ways and Means, Financial Services and Foreign Affairs, also plan to issue preservation letters to agencies that have provided information to Mr Mueller, such as the Justice Department, the FBI, the White House Counsel’s Office. They want the agencies to retain any memos, correspondence, or other information that could be relevant in their ongoing probes. The CIA, National Security Agency, Office of the Director of National Intelligence, and the Treasury and State departments also will receive letters.

Democratic lawmakers issued similar letters last year when Mr Trump fired his first attorney general, Jeff Sessions.

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Democrats believe Mr Mueller’s report and investigative materials will facilitate their efforts to further scrutinise Mr Trump’s campaign and administration, his personal finances and his business operations as they search for evidence of corruption or any effort to obstruct justice.

“There may be a lot of useful information in there, even if we think some things are unnecessarily redacted,” said representative Jamie Raskin, a senior member of the Judiciary and Oversight committees. But as a first order of business, when Mr Barr delivers a report on Mr Mueller’s probe to Congress, Mr Raskin said: “We plan to read it.”