WASHINGTON (SBG) — Former acting FBI Director Andrew McCabe acknowledged significant missteps in the investigation of Russian interference in the 2016 election, but he maintained officials were right to believe President Donald Trump might pose a threat to national security based on his behavior in early 2017.

“Let me be very clear. We didn’t open a case because we liked one candidate or didn’t like the other one. We didn’t open a case because we intended to stage a coup or overthrow the government,” McCabe said at a Senate Judiciary Committee hearing Tuesday.

McCabe was fired from the FBI in March 2018, days before his formal retirement, after the Department of Justice Office of the Inspector General determined he lacked candor in interviews with investigators about leaking sensitive information to the media. He has become a frequent target of criticism by President Trump, Judiciary Committee Chairman Lindsey Graham, R-S.C., and other Republicans for his role in the Russia probe.

“Republicans, don’t let Andrew McCabe continue to get away with totally criminal activity,” President Trump tweeted as the hearing began. “What he did should never be allowed to happen to our Country again. FIGHT FOR JUSTICE!”

McCabe acknowledged some errors were made in the course of the investigation, especially with regard to warrants to surveil former Trump campaign adviser Carter Page, and he called those failures “unacceptable.” However, he defended investigating Trump for ties to Russia during the campaign and for obstruction of justice after he fired then-FBI Director James Comey in 2017.

“Our concern that the president might be obstructing justice was verified by the Mueller report,” McCabe said, referring to special counsel Robert Mueller’s investigation.

A longtime senior official at the FBI, McCabe briefly served as acting director after Trump fired Comey. He personally approved the decision to investigate Trump over that firing, and he oversaw the Russia investigation until Mueller, a former director of the FBI, was appointed to head up an independent probe.

“We had many reasons at that point to believe the president himself might pose a danger to national security,” McCabe said.

In combative exchanges with GOP lawmakers, McCabe stood by the bureau’s work, defended his own integrity, and insisted suspicions about the actions of Trump and those around him were valid. He declined to comment on some documents and text messages, stressing that the Department of Justice had not allowed him to review his records before testifying.

The inspector general’s office conducted an extensive investigation of the Russia probe, which was known internally as “Crossfire Hurricane,” and determined there was sufficient predicate to open a counterintelligence case. Attorney General William Barr has disputed that conclusion, and the Department of Justice is conducting its own investigation of the origins of the probe.

The inspector general’s report identified nearly two dozen errors and omissions in the applications submitted to the Foreign Intelligence Surveillance Court to monitor Page. Agents who compiled the applications were accused of withholding information about sources and potentially exculpatory evidence about Trump aides.

McCabe was among the senior officials who authorized those applications, but he maintained he was unaware of the inaccuracies at the time. Had he known, he said, he would not have signed off on them.

“I fully support every effort to ensure that the FBI’s use of FISA maintains the high standards the court, and the American people, demand and deserve,” he said during his opening statement, and he reiterated the point under aggressive questioning from Graham.

McCabe defended the opening of the investigation of possible collusion between Trump’s 2016 campaign and the Kremlin after a Trump campaign aide told a foreign diplomat the Russian government would release damaging information about Democratic presidential nominee Hillary Clinton. He said there was no choice but to investigate, given Russia’s cyber activities targeting U.S. political institutions in the years before the election.

“We opened a case to find out how the Russians might be undermining our elections,” he said. “We opened a case because it was our obligation, our duty to do so. We did our job.”

McCabe was repeatedly pressed by Republicans about who should be held responsible for the flaws in the applications for FISA warrants for Page. The inspector general found numerous misstatements, misleading allegations, and oversights in the documents, and McCabe claimed he was “shocked and disappointed” by those conclusions.

“All of the people involved in this work should be and are being held accountable,” McCabe said, pointing to Tuesday’s hearing as proof of that.

Tuesday marked the fourth public hearing in the Republican-led investigation of Crossfire Hurricane and the officials who oversaw it. Comey, former Deputy Attorney General Sally Yates, and former Deputy Attorney General Rod Rosenstein testified at previous hearings.

“We’re going to find somebody accountable for something when it comes to Crossfire Hurricane,” Graham vowed.

One FBI attorney, Kevin Clinesmith has pleaded guilty to altering an email related to Page’s involvement with the Central Intelligence Agency, but McCabe testified he had seen no evidence that any other errors in the documents were intentional. While it excoriated McCabe and others, the inspector general’s probe did not conclude that the investigation of Trump’s campaign was driven by political bias.

“I am not aware of a single act, or even an allegation against anyone involved in the investigation that they committed a crime,” McCabe said, aside from Clinesmith.

Democrats on the committee accused Graham of stirring up conspiracy theories to validate President Trump’s claims that the Russia investigation was a hoax and that his campaign was illegally spied upon. They agreed mistakes were made, particularly in the handling of Carter Page, but they questioned the need for continued investigation of it at this point.

“How many more times do we need to say it?” said Sen. Dick Durbin, D-Ill.

Graham pressed McCabe over recently declassified documents that show officials were provided with reports that Russian intelligence had information in September 2016 about Democratic nominee Clinton’s campaign plotting to “stir up a scandal” by tying Trump to the hacking of Democratic emails. McCabe had not been aware of those unverified reports at the time, and it appears no investigation of them was conducted.

Democrats have alleged Director of National Intelligence John Ratcliffe selectively declassified several documents in the weeks before the presidential election to bolster Trump’s reelection bid. Former officials have cast doubt on the validity of the claims in the report, and even if they were true, McCabe suggested the FBI would have had no reason to probe the Clinton campaign’s political strategy.

Still, Graham contrasted the seeming dismissal of those reports with the FBI’s use of an unverified dossier of raw intelligence from former British spy Christopher Steele to obtain a warrant to surveil Page. Steele’s work was paid for by Clinton’s campaign, and many of his allegations have since proven inaccurate.

“You can’t have two standards,” Graham said, though he acknowledged the Russian information about Clinton might not have been true.

Sen. John Kennedy, R-La., insisted McCabe should have interviewed Steele personally once his research became a significant part of the Trump investigation. McCabe countered that questioning sources is not the role of senior FBI officials.

“I am not aware of a single instance of the deputy director of the FBI interviewing a source,” he said.

McCabe also stood by the FBI’s handling of an investigation of former Trump national security adviser Michael Flynn. Flynn was prosecuted for lying to FBI agents about conversations with the Russian ambassador during the transition and pleaded guilty to the charges, but the Department of Justice moved to drop the case prior to sentencing after his attorneys alleged prosecutorial misconduct.

Documents released by Flynn’s attorneys showed the FBI considered closing the Flynn investigation in early January 2017, but senior officials decided to keep it open. McCabe could not recall who made the decision to continue the probe, but he said he agreed with it.

“We had found very little, if any, incriminating evidence about General Flynn until, of course, we found very incriminating evidence about him,” he said.

Several Republican senators suggested Flynn’s contact with Russian Ambassador Sergei Kislyak was comparable to projected President-elect Joe Biden’s team communicating with foreign leaders during his transition. McCabe rejected that argument, noting that Flynn apparently lied to FBI investigators and Vice President Mike Pence about those conversations.

“Our concerns about General Flynn’s contact with Ambassador Kislyak was that the general might be maintaining some sort of hidden or deniable contact, and that he might have been the person in the campaign who coordinated contacts with the Russian government,” he said.

Sen. Kennedy described the conduct of McCabe, Comey, and other senior officials as an “incompetence tsunami” and asserted that they had done immense damage to the credibility of the FBI. McCabe denied that and placed blame instead on four years of political rhetoric attacking the agency.

“My colleagues and I never took any action to undermine our effectiveness, to undermine our oath… I deeply regret how politicized the FBI has become,” he said.

McCabe was fired for allegedly lying to investigators looking into leaks to the media about a probe of the Clinton Foundation in the weeks before the 2016 election. He has maintained he did not deliberately mislead them, and he has sued the Department of Justice over his removal.

“I was the subject of a biased, unfair, and deeply flawed investigation,” he said Tuesday.

Inspector General Michael Horowitz referred his findings on McCabe to federal prosecutors in Washington, D.C. for possible prosecution. The case was presented to a grand jury, but prosecutors told McCabe’s attorneys earlier this year that charges would not be filed.

“You think you did nothing wrong?” Sen. Marsha Blackburn, R-Tenn., asked.

“That’s correct,” McCabe replied.