Former FBI head Robert Mueller to oversee Trump-Russia investigation

The Department of Justice has appointed the former FBI director Robert Mueller as special counsel to investigate alleged ties between the 2016 presidential campaign of Donald Trump and Russian operatives. Mueller will also investigate questions of Russian intervention in the election generally.

Mueller, 72, was appointed FBI director by George W Bush and served 12 years, including for the majority of Barack Obama’s presidency. He said in a statement on Wednesday: “I accept this responsibility and will discharge it to the best of my ability.”

The move to appoint such a substantial figure, coming in a week of multiple reports that have rocked the White House, was welcomed by many Republicans and Democrats.

However, early Thursday, Donald Trump expressed displeasure on Twitter.

The tweets followed remarks he made at a public appearance on Wednesday at a coast guard academy in which he said no politician in history had been treated “worse or more unfairly”.

Special counsel is a position that exists under a statute that allows the attorney general or a deputy, if the attorney general is recused, to mount an independent investigation. This particular provision has been invoked only once before, in the Bill Clinton administration, when the former senator John Danforth was chosen to investigate the Branch Davidian siege outside Waco, Texas.

The position is different from an independent counsel, the role in which Ken Starr investigated Bill Clinton throughout the 1990s. The law authorising that position expired in 1999.

The deputy attorney general, Rod Rosenstein, made the decision to appoint Mueller. It was a letter from Rosenstein that the Trump administration initially presented last week as a central factor in the firing of James Comey as FBI director.

In an order announcing the appointment, Rosenstein explained he had taken the decision “to ensure a full and thorough investigation of the Russian government’s efforts to interfere in the 2016 presidential election”, including “any links and/or coordination between the Russian government and individuals associated with the campaign of President Donald Trump”.

“My decision is not a finding that crimes have been committed or that any prosecution is warranted,” Rosenstein wrote in a separate letter. “I have made no such determination. What I have determined is that based upon the unique circumstances, the public interest requires me to place this investigation under the authority of a person who exercises a degree of independence from the normal chain of command.”

In a statement released after Mueller’s appointment was announced, Trump said: “As I have stated many times, a thorough investigation will confirm what we already know – there was no collusion between my campaign and any foreign entity. I look forward to this matter concluding quickly. In the meantime, I will never stop fighting for the people and the issues that matter most to the future of our country.”

Kremlin spokesman Dmitry Peskov declined to comment on the appointment.

“There is nothing to comment on. It is an internal matter for the United States,” he said.

Also on Wednesday night, a 2016 exchange among members of the Republican House leadership surfaced in which majority leader Kevin McCarthy suggested that Donald Trump was on Vladimir Putin’s payroll.

According to a transcript of the conversation, which was first reported by the Washington Post, McCarthy said: “There’s … there’s two people, I think, Putin pays: [the California representative Dana] Rohrabacher and Trump … [laughter] … swear to God.” The House speaker, Paul Ryan, responded: “This is an off the record … [laughter] … NO LEAKS … [laughter] … alright?!”

After the Post’s report was published online, McCarthy tweeted: “This was an attempt at humor gone wrong.”

Ryan’s office also defended the remarks as a bad joke, saying in a statement: “No one believed the majority leader was seriously asserting that Donald Trump or any of our members were being paid by the Russians.”

Later on Wednesday, a third bombshell report surfaced, alleging that Michael Flynn, Trump’s now disgraced former national security adviser, had told the president’s transition team weeks before being appointed that he was under federal investigation for working, in secret, as a paid lobbyist for Turkey. The report from the New York Times shows that the Trump team was aware Flynn was being investigated much earlier than had been reported.

The White House was not aware of Rosenstein’s decision to appoint Mueller until after the order was signed, according to a justice department official. The news did not appear to have been shared on Capitol Hill either, with the House intelligence committee saying it had not been informed.

As special counsel, Mueller will command broad powers, including the power to subpoena documents and prosecute any crimes, independent of Congress. Calls on Capitol Hill for a special prosecutor in the investigation have percolated for months, but spiked after the firing of Comey, who was leading an FBI investigation into the matter. The independence of the investigation fell into question after the firing.

“A special counsel is very much needed in this situation,” the Republican senator Susan Collins said in a statement, calling Mueller “exactly the right kind of individual for this job”.

“Good move,” Senator Tim Kaine, the former vice-presidential candidate, wrote on Twitter. “Now let’s get some answers.” Fellow Democrats Chuck Schumer, the Senate minority leader, and Nancy Pelosi, the House minority leader, echoed the sentiment, with Pelosi calling Mueller “a respected public servant of the highest integrity”.

Trump has vehemently opposed the appointment of a special counsel, calling the investigation a waste of taxpayer money. White House press representatives were criticized for dismissing the need for a special prosecutor – a move seen as potentially encroaching on the justice department’s terrain.

The top officials from both parties on the House oversight and government reform committee, which had scheduled a hearing for next week at which Comey was invited to testify, praised the move.

“Mueller is a great selection,” the committee chairman, Republican Jason Chaffetz, tweeted. “Impeccable credentials. Should be widely accepted.”

The committee’s ranking member, Elijah Cummings, said Rosenstein had “made a solid choice in Mr Mueller, and I commend him for putting our country and justice system first. I urge Mr Mueller to follow the facts wherever they may lead – with integrity and independence.”

Prior to becoming FBI director, Mueller held a number of positions in the justice department under presidents of both parties. These included being appointed to serve as US attorney for the northern district of California under Bill Clinton in 1998, and overseeing the criminal division of the justice department as an assistant attorney general under George HW Bush.

After his time at the FBI, Mueller worked for the Washington-based private law firm WilmerHale, a position he has resigned.

A spokesperson for the former Trump campaign chairman Paul Manafort, whose ties in Ukraine and Russia have come under scrutiny, declined to comment to the Guardian on the Mueller appointment.