Justice Department Inspector General Michael Horowitz declared a “failure” by the entire “chain of command” involved in the FBI’s initial Trump-Russia investigation, in blistering testimony Wednesday that called out “basic and fundamental errors” at the bureau while stressing that his newly released report on the probe does not "vindicate" anyone.

The tone of the testimony, during a Senate Judiciary Committee hearing, ran counter to much of the coverage surrounding the report's release that zeroed in on a core finding that investigators found no evidence of political bias and were indeed justified in launching the 2016 probe.

FISA REPORT DROPS: 7 MAIN TAKEAWAYS FROM DOJ WATCHDOG'S RUSSIA PROBE REVIEW

Horowitz reaffirmed that finding, touted by congressional Democrats eager to defend the probe, at Wednesday's hearing. But his testimony as a whole amounted to a tough assessment of the bureau's actions -- and clarified that his two-year review on the Russia probe's origins and use of Foreign Intelligence Surveillance Act (FISA) warrants to surveil a Trump campaign aide did not close the book on the bias question either.

Under questioning, Horowitz said he could not outright determine whether bias was involved in the process of applying for a FISA warrant against former Trump adviser Carter Page.

"Can you say it wasn’t because of political bias?" Senate Judiciary Committee Chairman Lindsey Graham, R-S.C., asked.

"I do not know," Horowitz answered. He also said he was "not ruling it out," regarding the possibility that bias influenced those decisions.

In the run-up to the report's release, a number of leak-based media reports focused on the no-bias finding, painting the picture of an IG report that largely would go easy on the FBI. But the actual document highlighted numerous errors and missteps in the process, while Horowitz himself was highly critical -- several GOP lawmakers argued Wednesday that the report was in no way an exoneration for the FBI, with Sen. Mike Lee, R-Utah, calling such claims "crazy."

Former FBI Director James Comey essentially claimed vindication on Monday, declaring in the wake of the report that the criticism of the bureau's actions "was all lies" -- an assertion Graham brought up Wednesday.

"Is that a fair assessment of your report?" Graham asked Horowitz, citing Comey's vindication claim.

Horowitz bluntly replied: "I think the activities we found here don’t vindicate anybody who touched this FISA."

He did say, as the report reflected, that the so-called "Crossfire Hurricane" investigation was opened for an "authorized investigative purpose and with sufficient factual predication."

Horowitz reiterated in his testimony that he did not find any "documentary or testimonial evidence that political bias or improper motivation" influenced the opening of the bureau's Trump-Russia investigation or efforts to seek a FISA warrant to monitor Page.

Horowitz said Wednesday that while he did not make a determination as to the motive behind the efforts to obtain the FISA warrant for Page, he is referring "the entire chain of command" to the FBI and the Justice Department for further review of their "performance failures."

“We are deeply concerned that so many basic and fundamental errors were made by three separate, hand-picked investigative teams; on one of the most sensitive FBI investigations; after the matter had been briefed to the highest levels within the FBI; even though the information sought through the use of FISA authority related so closely to an ongoing presidential campaign; and even though those involved with the investigation knew that their actions were likely to be subjected to close scrutiny,” Horowitz said in his opening statement before the committee.

“We believe this circumstance reflects a failure not just by those who prepared the FISA applications, but also by the managers and supervisors in the Crossfire Hurricane chain of command, including FBI senior officials who were briefed as the investigation progressed,” he said.

Horowitz’s long-awaited report determined that the FBI complied with policies in launching the Trump-Russia investigation, but also flagged “significant concerns with how certain aspects of the investigation were conducted and supervised.” The inspector general said his team has “reviewed over 1 million records and conducted over 100 interviews, including several witnesses who only recently agreed to be interviewed" as part of the nearly two-year-long investigation.

READ: DOJ IG HOROWITZ STATEMENT TO SENATE JUDICIARY COMMITTEE ON RUSSIA PROBE REPORT

His 476-page report faulted the FBI for numerous errors in the FISA process, identifying at least 17 “significant inaccuracies and omissions” in the application and renewals for Page’s FISA warrant. The report said that Page’s FISA application omitted information that the FBI had obtained from another U.S. government agency detailing its prior relationship with Page, including that he had been “approved as an ‘operational contact’ for the other agency from 2008 to 2013.”

Horowitz noted that under FBI policy, every FISA application must contain a "full and accurate" presentation of the facts.

"Nevertheless, we found that members of the Crossfire Hurricane team failed to meet the basic obligation to ensure that the Carter Page FISA applications were scrupulously accurate," Horowitz said Wednesday.

DOJ WATCHDOG FINDS NO BIAS IN LAUNCH OF TRUMP-RUSSIA PROBE, BUT UNCOVERS 'SIGNIFICANT' FBI ERRORS

"Our review identified significant concerns with how certain aspects of the investigation were conducted and supervised, particularly the FBI's failure to adhere to its own standards of accuracy and completeness when filing [FISA] applications," Horowitz said, noting that he recommended the FBI "review the performance of all employees who had responsibility for the preparation or approval" of Page's FISA applications, including "senior officials in the chain of command" of the Crossfire Hurricane team for "any action deemed appropriate."

The report also revealed that the FBI did not have specific information corroborating allegations against Page from the now-infamous dossier authored by ex-British intelligence agent Christopher Steele. The inspector general found that the FBI was unable to “corroborate any of the specific substantive allegations against Carter Page contained in the election reporting and relied on in the FISA applications,” and learned “as early as January 2017” that there were “potentially serious problems” identified in Steele’s reporting -- but that the team continued using his information as a basis for Page’s FISA warrant.

"FBI leadership supported relying on Steele's reporting to seek a FISA order targeting Page after being advised of, and giving consideration to, concerns expressed by a Department attorney that Steele may have been hired by someone associated with a rival candidate or campaign," Horowitz said. The work was funded by Democrats and the Hillary Clinton campaign.

Horowitz stressed that the Steele reporting helped to push the Page FISA application "over the line" in terms of establishing probable cause for a FISA warrant, and noted that Steele's reporting "played a central and essential role in the decision to seek a FISA order."

Horowitz further said that parts of the Page FISA application "relied entirely on information from the Steele reporting to support the allegation that Page was coordinating with the Russian government on 2016 U.S. presidential election activities."

Horowitz’s report also found that the Crossfire Hurricane investigation was not properly sharing information with the Justice Department or other key figures who should have been privy to updated information. Horowitz revealed that the team failed to inform DOJ officials of information that was available to them at the time of the FISA applications. Much of that information was “inconsistent with, or undercut, the assertions contained in the FISA applications” and ultimately “resulted in inaccurate information being included” in Page’s FISA applications.

The hearing provided a forum for heated lines of questioning Wednesday, bringing the Russia probe back to Washington's center stage if only for a day, as most of Capitol Hill is consumed by the impeachment inquiry centering on Trump's interactions with Ukraine.

Senate Judiciary Committee Chairman Graham delivered a nearly 40-minute, unscripted and fiery opening statement accusing the FBI officials on the Crossfire Hurricane team of a "massive criminal conspiracy."

“What has been described as a few irregularities becomes a massive criminal conspiracy over time to defraud the FISA court, to illegally surveil an American citizen and keep an operation open against a sitting president of the United States -- violating every norm known to the rule of law,” Graham said.

Questioning Horowitz, Graham pressed the inspector general on the behavior and activities of the FBI officials involved in Crossfire Hurricane.

"The actions were not up to the standards of the FBI," Graham said, adding that he "certainly hopes" that the conduct is "not the way others are following in these practices."

But committee Ranking Member Dianne Feinstein, D-Calif., defended the FBI and echoed the paramount finding of Horowitz's report, which was released Monday.

"This was not a politically motivated investigation," she said. "There is no deep state."