Republicans have been fuming about they see as bias within the FBI, while Democrats say the surveillance abuse allegations are created to undermine special counsel Robert Mueller's sprawling investigation into the Trump campaign's ties to Russian meddling in the 2016 election.
The Department of Justice Office of the Inspector General will review the FBI's and DOJ's application to monitor former Trump campaign aide Carter Page during the election.
Last year, Sessions pledged to clamp down on leaks, noting that the Justice Department had more than tripled the number of active leak investigations since President Barack Obama left office and that the FBI had created a new counterintelligence unit to focus on such cases.
However, Trump said in February that an IG investigation would not be sufficient and a special counsel should be appointed.
The source in question is former British spy Christopher Steele, the author of the so-called Steele dossier, an explosive collection of memos alleging collusion between the Trump campaign and Russian Federation.
Rep. Jerrold Nadler of NY, the ranking Democrat on the House Judiciary Committee, called the investigation "a shame" and said Mr. Horowitz is being forced to chase a conspiracy theory. Steele's anti-Trump research was paid for by Democrat Hillary Clinton's campaign and the Democratic National Committee.
Under pressure from lawmakers to move more quickly, FBI Director Christopher Wray said Tuesday that he has now assigned 54 FBI staff to collecting documents for separate congressional investigations into the Justice Department initiated by the House Judiciary panel's Republicans.More news: Joel Embiid out for game after colliding with Markelle Fultz
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Democrats have said the investigations are a waste of money and time.
A two-page document filed by prosecutors for the Department of Justice's National Security Division, cited by the Minneapolis Star-Tribune, charges Terry James Albury with two counts of unlawfully disclosing and retaining national defense information.
The affidavits also pointed to discussions between Albury and a co-worker in 2015 in which they weighed reporting what they said was an inappropriate e-mail sent by another colleague.
According to search warrant applications obtained by the Star Tribune, Albury began working for the Federal Bureau of Investigation in 2000 and most recently was assigned to work on counterterrorism and other matters at the Minneapolis-St.
"Additionally, the OIG will review the DOJ's and FBI's relationship and communications with the alleged source as they relate to the FISC applications".
"We do not believe the Department of Justice is capable of investigating and evaluating these fact patterns in a fashion likely to garner public confidence", House Judiciary Chairman Bob Goodlatte of Virginia and House Oversight Chairman Trey Gowdy of SC wrote in a letter to Sessions earlier this month.