The revelation comes as Trump is already facing scrutiny about a potential abuse of power, including a House impeachment inquiry examining whether he withheld military aid to pressure the president of Ukraine to launch an investigation of former Vice President Joe Biden and his son Hunter.
The person who confirmed the criminal investigation Thursday was not authorized to discuss the matter publicly and spoke to The Associated Press on the condition of anonymity. It is unclear what potential crimes are being investigated, but the designation as a formal criminal investigation gives prosecutors the ability to issue subpoenas, potentially empanel a grand jury and compel witnesses to give testimony and bring federal criminal charges.
The Justice Department had previously considered it to be an administrative review, and Attorney General William Barr appointed John Durham, the U.S. attorney in Connecticut, to lead the inquiry into the origins of special counsel Robert Mueller's probe into Russian interference in the 2016 election. It's unclear when Durham's inquiry shifted to a criminal investigation.
Durham is examining what led the U.S. to open a counterintelligence investigation into the Trump campaign and the roles that various countries played in the U.S. probe. He is also investigating whether the surveillance methods and intelligence gathering methods used during the investigation were legal and appropriate.
Mueller's investigation shadowed Trump's presidency for nearly two years and outraged the Republican president, who cast it as a politically motivated "witch hunt." Mueller determined that the Russian government interfered in the 2016 election, but his investigation didn't find sufficient evidence to establish a criminal conspiracy between Trump's campaign and Russia. Mueller also examined 10 possible instances of obstruction of justice and has pointedly said he could not exonerate the president.
The New York Times first reported that Durham's inquiry had become a criminal investigation. The chairmen of the House Judiciary and Intelligence committees, which are leading the impeachment inquiry, said in a statement late Thursday that the reports "raise profound new concerns" that Barr's DOJ "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," Democratic Reps. Jerrold Nadler and Adam Schiff said.
The Justice Department has said Trump recently made several calls at Barr's request to foreign leaders, including Australian Prime Minister Scott Morrison, to help the attorney general with the Durham investigation.
Barr also traveled with Durham to Italy in August and September, and the two met with Italian intelligence officials to seek information about the activities of FBI agents assigned there, Italian Premier Giuseppe Conte said Wednesday.
The White House did not immediately respond to a request for comment Thursday.