WASHINGTON – Former acting-FBI Director Andrew McCabe said Thursday that top lawmakers "knew exactly" that the FBI had opened a counterintelligence inquiry into President Donald Trump when they were briefed on the status of the Russia investigation shortly after the 2017 firing of FBI Director James Comey.

McCabe, in an interview with reporters linked to the continuing rollout of his new book, offered additional details surrounding the bureau's extraordinary action against the president and the secret briefing provided to Congress' Gang of Eight outlining the bureau's decision.

"I am confident that everyone in the room knew exactly what we were doing," McCabe said, referring to the bipartisan group of lawmakers who are regularly briefed on classified intelligence matters.

While opening such an inquiry would have served as a blunt acknowledgment that federal investigators regarded the president as a possible threat to national security, McCabe said this week that none of the lawmakers objected to the action.

McCabe said the investigative action was ultimately prompted by Comey's firing and Trump's alleged efforts to persuade Comey to drop the agency's investigation into Russian contacts involving former national security adviser Michael Flynn.

The lawmakers have not responded to requests for comment.

Before briefing congressional leaders, McCabe said Thursday that Deputy Attorney General Rod Rosenstein also had been "fully advised" of the FBI's decision to launch the counterintelligence investigation.

McCabe said that he met personally with Rosenstein in the chaotic days after Comey's firing to notify him of the bureau's intentions.

"He didn't tell me to stop; he didn't tell me not to do it," McCabe said, referring to the deputy attorney general.

The Justice Department declined to comment on McCabe's account.

Rosenstein later accompanied McCabe to the congressional briefing where the deputy attorney general also disclosed his decision to appoint a special counsel – former FBI Director Robert Mueller – to take over the investigation that is now grinding to a close.

"I think Rod not only did the right thing, but the best thing he could have done under those circumstances," McCabe said. "How it turned out for me hasn't been great."

McCabe, who was tapped to serve as interim director following Comey's abrupt dismissal, was fired on the eve of his retirement last year for misleading Justice investigators about his contacts with reporters.

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The career FBI official is expected to challenge that dismissal in a lawsuit expected to be filed against the government soon.

McCabe has been a constant target of Trump's wrath, even though the president elevated him to acting FBI director's position following Comey's firing.

Trump took particular aim at McCabe's wife, asserting that her failed candidacy for the Virginia state Senate in 2015 and the support she received from allies of Hillary Clinton, represented a conflict for her husband as the FBI pursued its investigation of Clinton's use of a private email server.

More recently, Trump has focused on McCabe's book, suggesting that the work was akin to "treason."

McCabe has dismissed Trump's claims, saying that the book was subjected to a four-month pre-publication review by the FBI.

"We don't open cases for political reasons; we don't close cases for political reasons," McCabe said.