Then-FBI Director James Comey and then-FBI Deputy Director Andrew McCabe fought to include information from British ex-spy Christopher Steele’s dossier in the January 2017 intelligence community assessment on Russian election interference, according to a Justice Department watchdog report.

But the CIA “expressed concern” about using the former MI6 agent’s salacious and unverified allegations, and the allegations ultimately did not make an appearance in the body of the text of the assessment of Russia’s activities during the 2016 election.

The detailed examination of the clash between the FBI and the CIA comes from an FBI intelligence section chief and a supervisory intelligence analyst who appeared in Justice Department Inspector General Michael Horowitz's report about his Foreign Intelligence Surveillance Act investigation, which was released on Monday.

The CIA believed Steele’s dossier, which contained claims about Trump that, if true, could be used as blackmail, including a so-called pee tape, "was not completely vetted and did not merit inclusion in the body of the report.” The agency also dismissed Steele’s allegations as “internet rumor,” and the other intelligence agencies ultimately overruled efforts by Comey, McCabe, and the bureau to include Steele's work in the intelligence community assessment.

The revelations in Horowitz’s report appeared to put to rest long-simmering questions about whether it was Comey or intelligence officials such as former CIA Director John Brennan who pushed to include the Steele dossier in the high-profile assessment.

The assessment released on Jan. 6, 2017, concluded that “Russian President Vladimir Putin ordered an influence campaign in 2016 aimed at the U.S. presidential election” and that “Russia’s goals were to undermine public faith in the U.S. democratic process, denigrate Secretary Clinton, and harm her electability and potential presidency” while “Putin and the Russian Government developed a clear preference for President-elect Trump.”

At the behest of President Barack Obama, members of the FBI, CIA, and NSA, with oversight from the Office of the Director of National Intelligence, worked jointly to prepare the report. Horowitz said, “The FBI first shared Steele's reporting with other U.S. government intelligence agencies in December 2016” during the interagency drafting process. The FBI’s assistant director of counterintelligence, Bill Priestap, and the FBI’s intelligence section chief both wrote to the CIA to describe Steele as “reliable," and Horowitz said, “Whether and how to present Steele's reporting” in the assessment was “a topic of significant discussion” among the drafters.

On Dec. 16, 2016, the bureau’s intelligence section chief emailed the FBI that McCabe “wants the [Steele] reporting included in the submission with some level of detail." When he asked McCabe if the FBI’s submission to the joint draft team should be limited to Russian interference or should also include the dossier’s allegations against Trump, “McCabe understood President Obama's request for the ICA to require the participating agencies to share all information relevant to Russia and the 2016 elections, and the Steele election reporting qualified at a minimum due to concerns over possible Russian attempts to blackmail Trump,” according to Horowitz’s report. The same day, the intelligence section chief sent then-special agent Peter Strzok, Priestap, and another key FBI official a draft of the FBI’s proposed submission to the assessment, warning that “the minute we put the [Steele allegations] in there, it goes from what you’d expect the FBI to be collecting in a counterintelligence context to direct allegations about collusion with the Trump campaign.”

On Dec. 17, 2016, Comey reviewed and approved the FBI’s draft and emailed FBI team members about a call he had with Director of National Intelligence James Clapper the night before.

“I informed the DNI that we would be contributing the [Steele] reporting (although I didn’t use that name) to the [Intelligence Community] effort,” Comey wrote. “I stressed that we were proceeding cautiously to understand and attempt to verify the reporting as best we can, but we thought it important to bring it forward to the IC effort.”

The CIA pushed back against the FBI’s attempt to include it in the body of the assessment.

On Dec. 28, 2016, McCabe emailed Clapper’s principal deputy to continue his push to include the Steele information, saying, “There are a number of reasons why I feel strongly that it needs to appear in some fashion in the main body of the reporting.”

McCabe told Horowitz he sought to include it because of Obama’s request for all relevant information, the fact that Steele had ”a good track record” with the FBI even if his allegations weren’t verified, and because Steele’s dossier was already circulating in the government and media, and so he wanted to head off any leaks.

When Horowitz asked Comey whether he remembered discussing his efforts to include the Steele dossier with any of the intelligence community’s leadership, Comey recounted a meeting with Clapper, Brennan, and then-NSA Director Mike Rogers in which he said he was told “that the IC analysts found it credible on its face and gravamen of it, and consistent with our other information, but not in a position where they would integrate it into the IC assessment.”

Comey conceded to Horowitz that Steele’s dossier was “not ripe enough, mature enough, to be in a finished intelligence product.”

Horowitz said that the final intelligence community assessment in January 2017 “included a short summary and assessment of the Steele election reporting” in an appendix and that the intelligence agencies concluded that there was "only limited corroboration of the source's reporting” and that Steele's allegations were not used “to reach analytic conclusions of the CIA/FBI/NSA assessment.”

Republican Kentucky Sen. Rand Paul has pinned the blame on Brennan. In March, he tweeted, "A high-level source tells me it was Brennan who insisted that the unverified and fake Steele dossier be included in the Intelligence Report."

Watergate sleuth Bob Woodward said in an interview this year, “I think it was the CIA pushing this.”

Brennan said in February 2018 that the dossier “did not play any role whatsoever in the intelligence community assessment that was done and that was presented to then-President Obama and then-President-elect Trump.” Brennan said that “there were things in that dossier that made me wonder whether they were in fact accurate and true” and said that “it was up to the FBI to see whether or not they could verify any of it.”

Trey Gowdy, a former Republican congressman, suggested earlier this year that Comey emails in December 2016 would be key to answering these questions.