Justice Department Inspector General Michael Horowitz said Wednesday that he was concerned the FBI did not reevaluate whether to continue investigating a former Trump campaign adviser as agents failed to uncover evidence of wrongdoing in late 2016, and that missteps in the case might indicate a broader problem within the bureau.

Testifying at a Senate Homeland Security and Governmental Affairs Committee hearing, Horowitz criticized how the FBI handled its probe of former Trump campaign adviser Carter Page, asserting that agents used inaccurate information to obtain court orders to surveil Page, even as they discussed among themselves that the investigation was coming up empty.

While Horowitz said he did not find evidence of those problems “infecting” the rest of the FBI’s investigation into whether the Trump campaign coordinated with Russia to influence the 2016 election, he asserted he was so alarmed that he launched a broader review of the FBI’s use of the Foreign Intelligence Surveillance Court.

“The concern here is, this is such a high-profile, important case,” Horowitz testified. “If it happened here, is this indicative of a wider problem?”

The hearing is the second time Horowitz has discussed his assessment of the FBI’s 2016 investigation of the Trump campaign. As with his last appearance before the Senate Judiciary Committee, his remarks offered fodder for Democrats and Republicans to validate their divergent views of the politically sensitive probe, which was ultimately taken over by special counsel Robert S. Mueller III.

Horowitz said that the bureau was justified in opening the investigation, though he noted the threshold for doing so was low. He also said he found no evidence of political bias affecting the inquiry.

But Horowitz said, too, that as the investigation went along and the FBI applied to surreptitiously monitor Page, the bureau included “significant inaccuracies” and omitted important information in its bids to do so. He said he found evidence that agents discussed “not finding anything with regards” to Page but pressed ahead anyway, instead of reassessing whether the probe was worthwhile.

“We’ve got agents talking with one another about why is Page even a subject anymore,” Horo­witz said.

That assertion is important because Republicans have suggested that even if the FBI’s investigation was opened legitimately, it should have been shut down long before Mueller was appointed.

Sen. Ron Johnson (R-Wis.), chairman of the Homeland Security Committee, said in his opening statement that he believes the inspector general report shows that the FBI’s Russia investigation should have been shut down “within the first few months of 2017.” Instead, he said, the Trump administration was “tormented for over two years . . . all based on a false narrative.”

The probe was opened in the summer of 2016; Mueller submitted his final report to the attorney general in March. The special counsel did not find enough evidence to allege that the Trump campaign conspired with the Kremlin to influence the election and declined to come to a conclusion on whether Trump had sought to obstruct the probe.

Under questioning from Sen. Gary Peters (D-Mich.), Horowitz noted he found no evidence that the missteps in the Page case sullied the FBI’s other work.

The FBI’s opening of the umbrella investigation involving the Trump campaign was based not on Page, but a different Trump campaign adviser, George Papadopoulos, whose boasts to an Australian government official about the Russians potentially having dirt on Trump’s opponent, Hillary Clinton, sparked the bureau’s interest.

Horowitz said he was unable to get satisfactory explanations for some of the FBI’s misconduct, and certain witnesses agreed to cooperate only late in the investigation.

Conservatives have also noted that Horowitz’s report is not the last word. Attorney General William P. Barr tapped the top federal prosecutor in Connecticut, U.S. Attorney John Durham, to do a similar review of the Russia case. Barr and Durham have said they disagree with some of what Horowitz found, especially on the FBI’s basis to initiate the investigation. Horowitz said such disagreement “isn’t a problem” and noted that no one seemed to be disagreeing with the facts he had found, only the conclusions he had drawn from those facts.

President Trump, meanwhile, has emphasized Horowitz’s damaging findings for the FBI and attacked the inspector general.

“As bad as the I.G. Report is for the FBI and others, and it is really bad, remember that I.G. Horowitz was appointed by Obama,” Trump tweeted Sunday. “There was tremendous bias and guilt exposed, so obvious, but Horowitz couldn’t get himself to say it. Big credibility loss. Obama knew everything!”

While Horowitz’s report undercut some of Trump’s most forceful attacks on the Russia investigation, his assertions on the FBI’s use of the Foreign Intelligence Surveillance Court could have wide-ranging implications.

On Tuesday, the court issued a rare public order in response to Horowitz’s findings, calling out the FBI for its wrongdoing and ordering the agency to submit a plan by Jan. 10 “to ensure that the statement of facts in each FBI application accurately and completely reflects information possessed by the FBI that is material to any issue presented by the application.”

“The frequency with which representations made by FBI personnel turned out to be unsupported or contradicted by information in their possession, and with which they withheld information detrimental to their case, calls into question whether information contained in other FBI applications is reliable,” presiding judge Rosemary M. Collyer wrote.

Some lawmakers have suggested that they might consider stripping the Foreign Intelligence Surveillance Court of its legal basis if it and the bureau do not institute changes. Horowitz is doing a broader review of the FBI’s applications to the court, and FBI Director Christopher A. Wray has promised to implement corrective steps. He said Wednesday that he felt Horowitz’s report “describes behavior and performance that I consider unacceptable and also unrepresentative of who we are as an institution.”

Johnson called the court’s statement a “dramatic rebuke” of the FBI’s conduct. He said his previous belief that applications to the Foreign Intelligence Surveillance Court were reviewed rigorously and at the highest levels of law enforcement had been “completely blown.”

“I think the FISA court is in jeopardy, personally,” Johnson said, referring to the Foreign Intelligence Surveillance Act.

Appearing at a news conference in Detroit on Wednesday, Barr, the attorney general, said the act was a “critical tool to protecting Americans” and noted that he and Wray were working to implement changes to address the inspector general’s concerns.

“We are committed to preserving FISA, and we think all Americans should be committed to preserving FISA,” he said.