WASHINGTON – The Justice Department's politically-charged inquiry into the origins of the Russia investigation has shifted to a criminal probe, a person familiar with the matter said late Thursday.

The move is all but certain to fuel fresh suspicion among Democrats that Attorney General William Barr is providing political cover to President Donald Trump, who has repeatedly disparaged former special counsel Robert Mueller's two-year investigation into the Kremlin's intervention in the 2016 election as a "witch hunt."

Barr launched the inquiry in April into whether federal investigators abused their surveillance authority as they sought to understand Russia's interference during the 2016 presidential campaign.

Barr later appointed Connecticut's chief federal prosecutor, John Durham, to manage the investigation.

It was unclear Thursday evening when the examination moved from an administrative review to a criminal investigation. The development was first reported by The New York Times.

Rep. Mark Meadows, R-N.C., praised Barr after news of the criminal investigation broke.

“If true, this shows Bill Barr is doing EXACTLY his job: following the facts,” Meadows, former chairman of the House Freedom Caucus, said on Twitter. “Those who damaged America and broke the law to spread this hoax are about to face accountability.”

In a joint statement, Reps. Jerrold Nadler, D-N.Y., and Adam Schiff, D-Calif., two House chairmen leading wide-ranging investigations of the president, said the news reports raise concerns that Barr’s Justice Department “has lost its independence and become a vehicle for President Trump’s political revenge.”

"If the Department of Justice may be used as a tool of political retribution or to help the President with a political narrative for the next election, the rule of law will suffer new and irreparable damage,” the chairmen said.

James Baker, the FBI’s former general counsel who oversaw the launch of the Russia investigation, and Michael Bromwich, attorney for former FBI deputy director Andrew McCabe, declined to comment.

Barr: 'I think spying did occur'

When he first announced the inquiry during testimony before a Senate subcommittee in April, Barr expressed concern about the FBI's use of surveillance of associates of Trump during the presidential campaign.

At the time, Barr said he did not know whether officials had done anything wrong.

The attorney general said he planned to examine the "genesis and the conduct" of the FBI's investigation into possible ties between the Trump campaign and Russia.

"Spying on a campaign is a big deal," Barr told lawmakers then. "I think spying did occur. The question is whether it was adequately predicated."

Durham has led several high-profile special investigations, including an examination of the FBI's handling of criminal informants in Boston during the Clinton administration, which led to the prosecution of former agent John Connolly. He led an inquiry during the George W. Bush administration into the CIA's destruction of videotapes depicting the torture of terror detainees.

'The FBI doesn't spy':Comey slams Barr for spying claim, 'misleading' Mueller summary

Trump has asked world leaders to assist inquiry

Barr has personally overseen the inquiry and has sought assistance from law enforcement partners around the globe, including those in Italy and the United Kingdom.

White House officials confirmed last month that Trump had asked multiple countries, including Australia, to help Barr's inquiry.

Spying, treason and politics:President Trump ups the stakes in Russia probe battle despite scant evidence

Australia played a pivotal role in the FBI's decision to launch the initial investigation into Russia interference in 2016.

Australia's top diplomat in the United Kingdom passed information to U.S. authorities after a meeting with George Papadopoulos, a Trump campaign foreign policy adviser. The diplomat said Papadopoulos confided that Russians were offering damaging information on then-Democratic presidential candidate Hillary Clinton.

Papadopoulos ended up serving two weeks in prison for lying to FBI agents about his interactions with a Russian national while working for the Trump campaign. Trump has dismissed Papadopoulos as a low-level campaign aide.

He was the first former Trump aide to be sentenced in Mueller's investigation of Moscow's interference operation.

The disclosure about Barr's probe comes as a House impeachment inquiry has elicited damning testimony from current and former Trump administration officials who have outlined the president’s efforts to press Ukraine to investigate political rival and former Vice President Joe Biden – or risk losing millions in military aid.

The impeachment investigation has focused on Trump's July 25 telephone call with Ukraine President Volodymyr Zelensky. Trump repeatedly invoked Barr's name during the call, indicating that the attorney general would assist a Ukrainian inquiry into an energy company where Biden's son, Hunter Biden, served as a board member.

Neither the former vice president nor his son have been accused of wrongdoing by the Ukrainian government.

Justice Department officials said Barr didn't know Trump had suggested that he work with the Ukrainian president until weeks after the call, and Barr didn't contact Ukrainian officials.

Related probe into surveillance warrants is wrapping up

The Justice Department's inspector general has been conducting a parallel examination to Barr's and is likely to release its own report in a matter of weeks.

Inspector General Michael Horowitz told lawmakers Thursday that his report on the use of surveillance warrants during the Russia investigation is going through a review process that’s “nearing completion,” according to a letter obtained by CBS News.

Horowitz told lawmakers he expects the final report to be released to the public “with few redactions.”

Horowitz launched his review in March 2018 in response to requests from lawmakers and then-Attorney General Jeff Sessions. The inspector general looked into whether the FBI violated the Foreign Intelligence Surveillance Act, or FISA, when it sought court-ordered surveillance of former Trump campaign aide Carter Page in late 2016 as part of the Russia investigation.

The surveillance of Page has long animated Trump and Republicans and has fueled claims of spying – even treason – against former top law enforcement officials.