For the best part of two years, America and the rest of the world have waited for Robert Mueller to complete his report into Russia’s alleged interference in the 2016 election and possible collusion between Moscow and the Trump campaign.

Now he has done so, and attorney general William Barr has said he could update members of congress with details as early as this weekend.

“The special counsel has submitted to me today a ‘confidential report explaining the prosecution or declination decisions’ he has reached,” he on Friday wrote to members of Congress, including Republicans Lindsey Graham and Doug Collins, and Democrats Jerrold Nadler and Dianne Feinstein, the chairs and ranking members of the two judiciary committees.

“I am reviewing the report and anticipate that I may be in a position to advise you of the special counsel’s principal conclusions as soon as this weekend.”

He added: “Separately, I intend to consult with deputy attorney general Rod Rosenstein and special counsel Mueller to determine what other information from the report can be released to Congress and the public consistent with the law.”

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

So – after all that – what happens next?

All eyes on Bill Barr:

Barr, who oversees the investigation, has said he wants to release as much information as he can about the inquiry, “as is consistent with the law”, including the Special Counsel regulations, and the Department’s long-standing practices and policies. “I remain committed to as much transparency as possible, and I will keep you informed as to the status of my review.”

Barr has said he envisions two reports, and only one for congressional and public consumption.

Barr has said he takes seriously the “shall be confidential” part of the regulations governing Mueller’s report. He has noted that department protocol says internal memos explaining charging decisions should not be released.

During his confirmation hearing, Barr said he will draft, after Mueller turns in his report, a second one for the chairman and ranking members of the House and Senate Judiciary committees. But here again, the regulations provide little guidance for what such a report would say.

The attorney general is required only to say the investigation has concluded and describe or explain any times when he or Rosenstein decided an action Mueller proposed “was so inappropriate or unwarranted” that it should not be pursued.

Pressure:

Pressure is already mounting from Democrats for it to be made completely public. All of the major Democrats running for 2020 made such demands, as has Democratic senator Mark Mark Warner, vice chairman of the Senate intelligence committee.

Senate Democratic Leader Chuck Schumer and House Speaker Nancy Pelosi, sent out a joint statement calling on Mr Barr “to make the full report public and provide its underlying documentation and findings to Congress”.

“The White House must not be allowed to interfere in decisions about what parts of those findings or evidence are made public,” they said.

Some senior Republicans have also demanded the report be made public. Senator Chuck Grassley said releasing the report would “to finally put an end to the speculation and innuendo that has loomed over this administration since its earliest days”.

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White House:

Mr Trump has yet to comment on the report. White House press secretary Sarah Sanders said in a statement: “The next steps are up to Attorney General Barr, and we look forward to the process taking its course. The White House has not received or been briefed on the Special Counsel’s report.”

Mr Trump’s lawyers lawyers say they were “pleased” that the special counsel has delivered his report.

Rudy Giuliani and Jay Sekulow issued their joint statement within minutes of Barr’s letter to key members of Congress. “We’re pleased that the Office of Special Counsel has delivered its report to the attorney general pursuant to the regulations. Attorney General Barr will determine the appropriate next steps.”

But Mueller’s report, still confidential, sets the stage for big public fights to come, including in all likelihood, in federal court.

It’s not clear how much of the report will become public or provided to Congress. It is likely the White House will claim executive privilege permits the president to determine how transparent to be. Indeed, Mr Giuliani has also raised the prospect Trump legal team could try to invoke executive privilege to prevent the disclosure of any confidential conversation the president has had with his aides.

This week, asked by reporters whether it should be made public, Mr Trump said he would be “happy” if the report is made public. “Let it come out, let people see it, that’s up to the attorney general....and we’ll see what happens,” he said.

Legal cloud over the president.

Mr Trump still has to contend with state and federal investigations in New York even with the Russia investigation complete.

Some legal observers have ling said the greater threat to the presidency could stem from ongoing investigations in New York.

Federal prosecutors in Manhattan are still investigating hush money payments that former Trump attorney Michael Cohen arranged to women who claimed affairs with Trump.

Another inquiry is looking at the president’s inaugural committee and whether it received illegal foreign contributions.

The US Justice Department has held for nearly a half-century that a sitting president is immune from indictment. But he could be charged after leaving office. Mr Trump has denied breaking any laws.

Impeachment?

As Mr Mueller’s report was handed in, a spokesperson for the Department of Justice said the special counsel was not recommending any further indictments. It is possible some indictments remain sealed and could be unsealed later.

Democrats will now have to wait and see the details of the report to decide whether it has found the president has obstructed justice or acted in a way that would merit them seeking his impeachment. Democrats are very cautious of taking such a step, aware as they are of the potential political backlash.