The Department of Justice announced on Wednesday evening former FBI director Robert Mueller will serve as a special counsel to oversee the FBI’s investigation of the Russian government’s efforts to influence the 2016 presidential election.

The investigation will also examine “any links and/or coordination between the Russian government and individuals associated with the campaign of President Donald Trump,” according to the order creating the position.

It’s an official concession from the Justice Department that the Russian intervention in the 2016 presidential election was an extraordinary circumstance, and that bringing in an outsider to oversee the investigation is in the public interest. Rod Rosenstein, the second-in-command at the Justice Department, made the decision. That’s because he oversees the Russia investigation, due to Attorney General Jeff Sessions’ recusing himself from it.

President Trump said in a statement he hoped the investigation would concluded “quickly.”

“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,” he said. “ 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.”

Mueller will have the power to bring in staff from outside the Justice Department to help with the investigation, and will have all the authority of a U.S. Attorney. He will also be able to request a budget for the investigation, which Rosenstein will ultimately approve.

“In my capacity as acting Attorney General, I determined that it is in the public interest for me to exercise my authority and appoint a special counsel to assume responsibility for this matter,” he said in a statement. “My decision is not a finding that crimes have been committed or that any prosecution is warranted.”

“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.”

A special counsel has only been appointed once before, when then-Attorney General Janet Reno named John Danforth to investigate allegations of a coverup related to the Waco siege.

The DOJ release noted Mueller would resign from the private law firm where he currently works to avoid any conflicts of interest.

Mueller’s appointment comes after months of increasingly vocal—and bipartisan—calls for a probe into Russian meddling in the 2016 election independent from leaders at the Justice Department, some of whom supported Trump’s candidacy.

Chief among those leaders is Attorney General Jeff Sessions, who recused himself from the Russia investigation in March. Sessions was an early Trump supporter and a surrogate for his campaign, and acknowledged a potential conflict of interest, or the perception thereof, when he handed the reins of the investigation to a top deputy.

Calls for a special counsel intensified last week after Trump fired FBI director James Comey and days later admitted that he had weighed the persistence of the agency’s Russia investigation in doing so.

In the days since, news reports have revealed that Trump, in private meetings with Comey, asked the FBI director to pledge loyalty to him, and pushed him to drop the FBI’s probe into retired Army Gen. Mike Flynn, Trump’s former National Security Adviser. Flynn resigned in February after it was revealed that he had failed to disclose discussions with Russia’s ambassador to Washington regarding U.S. sanctions against the country. He and a number of business associates have since been subpoenaed as part of a separate congressional investigation into the Trump campaign’s Russia contacts.

Demands for a special counsel to take the reins of DOJ’s probe, and the steady drip of damning information underlying those calls, threatened to cast a shadow over the early tenure of Comey’s successor, who has not yet been selected.

Though it may sate some congressional Democrats and other Trump critics, a DOJ-appointed special counsel lacks the degree of independence enjoyed by special prosecutors of the 1980s and 1990s, which served in statutory positions created by an act of Congress that freed them from DOJ authority.

Modern special counsels, by contrast, serve at the direction and pleasure of the attorney general or a designated deputy.

“Mueller’s appointment would come from DOJ authority within the Executive Branch,” explained attorney Mark Zaid. “So technically, as far as I understand it, Mueller reports to DOJ leadership.”

In the immediate hours after the announcement, reactions from House Republicans interviewed by The Daily Beast ranged from resigned to defiant.

“At some level, it became more and more inevitable,” said Rep. Mark Sanford. “Based on feedback that I’ve gotten in our district, a lot of people are concerned that regardless of what the committees came up with, there would probably still be questions. It’s probably a wise move that’s vital to establishing… people’s belief that whatever we come up with in Washington is in fact the case.”

Rep. Peter King said the decision to appoint a special counsel was “fine” but added, it wasn’t really necessary.

“There’s no evidence of collusion at all,” he said. “Just a rabid press corps and a very intense Democratic Party.”

Rep. Dana Rohrabacher, who has been called “Putin’s favorite congressman” said the appointment wouldn’t change his belief that “there’s not been any there…in terms of any charges against the Russians.”

He added, “I hope they get down and look at it very closely and then put everything up and show people that there’s nothing there.”

—Tim Mak contributed to this report.