Department of Justice Inspector General Michael Horowitz on Wednesday faced tough questioning from lawmakers on both sides of the Senate Judiciary Committee about his nearly 500-page report examining the origins of the Russia investigation.

In his opening statement, Chairman Lindsey Graham, R-S.C., in remarks directed at Horowitz, lambasted the FBI’s handling of the probe.

“You were able to uncover and discover abuse of power I never believed would actually exist in 2019,” Graham said. “How bad is it? It was as if J. Edgar Hoover came back to life. The old FBI that had a chip on its shoulder and wanted to intimidate people and find out what was going on in your life and the law be damned.”

“It was Trump today, it could be you or me tomorrow,” Graham warned.

“Whether you like Trump, hate Trump, don’t care about Trump, you look at this as more than a few irregularities. Because if this becomes a ‘few irregularities’ in America, then God help us all.”

Horowitz’s report, released Monday, determined the FBI’s investigation into Russian interference in the 2016 U.S. election was launched with an authorized purpose, despite significant allegations of wrongdoing in how agents handled the counterintelligence probe of the Trump campaign.

Horowitz also told the committee no confidential human sources were placed inside of the Trump campaign, and that he found no evidence the FBI ‘wiretapped’ Trump either before or after the 2016 election.

“We did not find any documentary or testimonial evidence that political bias or improper motivation influenced the FBI’s decision to conduct these operations [involving confidential human sources]. Additionally, we found no evidence that the FBI attempted to place any CHSs (confidential human sources) within the Trump campaign, recruit members of the Trump campaign as CHSs, or task CHSs to report on the Trump campaign,” he said.

Asked about Attorney General William Barr’s recent statements splitting from Horowitz’s finding that the investigation into the Trump campaign had an adequate predicate, Horowitz responded, “we stand by our findings.”

However, Horowitz acknowledged that the FBI didn’t do all it could to “meet the basic obligation to ensure that the (former Trump campaign adviser) Carter Page FISA applications were ‘scrupulously accurate.'”

“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 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,” he testified.

Horowitz said he was deeply troubled by the altering of a document used in the FISA process, as detailed in the report.

“I have not seen an alteration of an email impacting a court document like this,” Horowitz told Sen. Ted Cruz, R-Texas. But he wouldn’t agree that the report shows a “grotesque abuse of power,” as Cruz alleged earlier.

“We did not reach a conclusion like that. So, I wouldn’t agree with that at this point. From my standpoint, people can have that viewpoint. But that was not our conclusion,” he said.

Sen. Dianne Feinstein, D-Calif., said the IG report “conclusively refutes” claims of political motivation by President Donald Trump and strong suggestions of that from Barr.

“There is no ‘Deep State.’ Simply put, the FBI investigation was motivated by facts, not bias,” Feinstein said.

Horowitz also said that he did not find any evidence that the FBI tried to “overthrow” the president as he has claimed and did not tap the phones at Trump Tower.

Horowitz also said he was “surprised” by a statement from U.S. Attorney John Durham on Monday taking issue with his findings. Durham is conducting a broader investigation into how the Russia investigation began. Horowitz said Durham told him in November that he “didn’t necessarily agree” that there was justification to open a full counterintelligence investigation into the Trump campaign.

Durham also told him, Horowitz testified, that the information used to support the preliminary investigation opened by the FBI was “sufficient.”

In a statement released Monday, Durham said he had “advised the Inspector General that we do not agree with some of the report’s conclusions as to predication and how the FBI case was opened.” But the statement made no mention of his support for the opening of the preliminary investigation, as Horowitz claimed.

A spokesperson for Durham told ABC News he has “no comment” on Horowitz’s characterization of their November conversation.

Elsewhere in his testimony, Horowitz also revealed his office still had an ongoing investigation into contacts Trump’s current personal lawyer, Rudy Giuliani, had with the New York FBI field office and whether agents may have improperly leaked information to Giuliani or other journalists about the Clinton email investigation before the 2016 election.

“We are looking at still that question,” Horowitz said in response to Sen. Dick Durbin D-Ill. “Our investigation is ongoing.”

Earlier, in an interview with “CBS This Morning” on Wednesday, Grahamsaid that he “really believes” that the FBI wanted to “bring down the president.”

“It doesn’t matter why they did it. I want people to understand that cops can’t cheat. Cops can’t lie. They have to play by the rules, even if you don’t like Trump you should play by the rules because it could be you next time, not Trump,” Graham continued.

Similar statements, were echoed by Barr on Tuesday, in a stunning interview where he blasted the Russia investigation as a “travesty” and that Horowitz’s findings left open the possibility for “bad faith” on the part of FBI agents involved.

“From a civil liberties standpoint, the greatest danger to our free system is that the incumbent government used the apparatus of the state, principally the law enforcement agencies and the intelligence agencies, both to spy on political opponents, but also to use them in a way that could affect the outcome of the election,” Barr said in an interview with NBC News.

FBI Director Christopher Wray, in an exclusive broadcast interview Monday with ABC News, lamented “actions described in this report that [he] considered unacceptable and unrepresentative of who we are as an institution.”

But, he said it was “important that the inspector general found that, in this particular instance, the investigation was opened with appropriate predication and authorization.”

At least one Democrat on the committee blasted Barr’s theories.

“This report shows there was a proper predicate for the FBI to investigate Russia’s malign influence on the 2016 election and contacts with the Trump campaign. That puts to rest President Trump’s accusations of a deep state conspiracy, and no amount of spin from Attorney General Barr, the White House, or congressional Republicans can change that. Barr’s decision to question the report in the media says a lot about Attorney General Barr,” Sen. Sheldon Whitehouse, D-R.I., said in a statement on Monday.

“The Inspector General is an important defender against political influence over law enforcement—a regrettable tendency under Attorney General Barr. I hope the Inspector General turns his attention to other allegations of politically motivated investigations by this administration.”