Former acting FBI Director Andrew McCabe Andrew George McCabeGraham: Comey to testify about FBI's Russia probe, Mueller declined invitation Barr criticizes DOJ in speech declaring all agency power 'is invested in the attorney general' GOP votes to authorize subpoenas, depositions in Obama-era probe MORE and Deputy Attorney General Rod Rosenstein Rod RosensteinDOJ kept investigators from completing probe of Trump ties to Russia: report Five takeaways from final Senate Intel Russia report FBI officials hid copies of Russia probe documents fearing Trump interference: book MORE opened an obstruction of justice investigation into President Trump Donald John TrumpOmar fires back at Trump over rally remarks: 'This is my country' Pelosi: Trump hurrying to fill SCOTUS seat so he can repeal ObamaCare Trump mocks Biden appearance, mask use ahead of first debate MORE before special counsel Robert Mueller Robert (Bob) MuellerCNN's Toobin warns McCabe is in 'perilous condition' with emboldened Trump CNN anchor rips Trump over Stone while evoking Clinton-Lynch tarmac meeting The Hill's 12:30 Report: New Hampshire fallout MORE's appointment, CNN reported Friday.

McCabe took the step to launch the investigation into the president after Trump fired his predecessor, former FBI Director James Comey James Brien ComeyDemocrats fear Russia interference could spoil bid to retake Senate Book: FBI sex crimes investigator helped trigger October 2016 public probe of Clinton emails Trump jabs at FBI director over testimony on Russia, antifa MORE, in May 2017, two sources told the cable news outlet.

ADVERTISEMENT

The FBI’s justification for the probe reportedly included Trump’s reported conversation with Comey in the Oval Office where he asked for an investigation into former national security adviser Michael Flynn to be dropped.

The Washington Post first reported last year the launch of an obstruction investigation, but sources elaborated to CNN how top law enforcement officials were frantic after Comey was fired.

They were reportedly concerned about Trump’s behavior and considered him a leader who might need to be reined in, sources told CNN.

Officials reportedly tossed around various ideas about how to handle the investigation, including a discussion about Rosenstein wearing a wire to talk to Trump, a report which Rosenstein later denied.

A source within the Justice Department rejected the notion that Rosenstein tried to curb Trump, telling CNN that he "never said anything like that."

A spokeswoman for McCabe did not prove a comment to the network.

McCabe and Rosenstein, on the day that the special counsel was appointed, briefed the Gang of Eight Republican and Democratic congressional leaders and the heads of each intelligence committee.

Mueller was appointed just eight days after Comey's firing to investigate alleged Russian interference in the 2016 election and potential collusion between the Trump campaign and Moscow.

The president and his allies have frequently railed against the special counsel investigation and the officials who launched it, calling it a "witch hunt."

McCabe was fired from the FBI in March and Trump tweeted a picture showing Rosenstein behind bars just last week.

"It's shocking that the FBI would open up an obstruction case for the President exercising his authority under Article II," Trump’s attorney Rudy Giuliani told the outlet.