(CNN) Former FBI Director James Comey, after facing aggressive questioning from members of Congress on Friday, expressed exasperation that he had been dragged to a private setting on Capitol Hill to be asked questions about the Hillary Clinton email investigation that ended more than two years ago.

"After a full day of questioning, two things are clear to me: One, we could have done this in (an) open setting," said Comey in a news conference with reporters. "And two: When you read the transcript, you will see that we are talking again about Hillary Clinton's emails, for heaven's sakes."

"So I'm not sure we need to do this at all, but I'm trying to respect the institution and to answer questions in a respectful way," he added.

Comey left the meeting just after 4:30 p.m. ET and said he'd agreed to come back to speak with Congress on December 17.

Comey had fought the congressional subpoena in court, pushing for a public hearing before settling for some concessions. A transcript of the interview with members of the House Judiciary and Oversight committees will be released as soon as possible, perhaps in the next 24 hours.

Emerging from the closed interview, House Democrats said Comey took strong exception to President Donald Trump's attacks over the FBI, saying they hurt morale at the Justice Department.

Comey declined to answer a reporter's question regarding the President's firing of former Attorney General Jeff Sessions, but he took umbrage at Trump's repeated critiques of the department.

"I think the President's attacks on the Justice Department broadly and the FBI are something that no matter what political party you're in, you should find deeply troubling and continue to speak out about," said Comey, urging the public to "not become numb to attacks on the rule of law."

'A little bit tense'

Illinois Rep. Raja Krishnamoorthi said the mood was "a little bit tense" but that said it was appropriate for Comey not to answer questions related to the Clinton email investigation. He also said Comey's testimony is consistent with his book and previous Hill testimony.

Comey said that given the chance he wouldn't have handled the Russia or Clinton probes differently than he did, according to Rep. Jimmy Gomez, a California Democrat.

Trump fired Comey in May 2017, a move that led the Justice Department to appoint Robert Mueller as special counsel to investigate Russian interference in the 2016 election, including potential collusion between Trump's campaign associates and Russian officials.

Since he was fired, Comey has publicly testified on Capitol Hill, spoken to the media numerous times and released his book on "ethical leadership" and his FBI career.

Over the summer, the Department of Justice inspector general released an extensive report criticizing Comey's handling of the Clinton email investigation and calling some of his actions "extraordinary and insubordinate," but the report did not find that he was motivated by political bias.

That same report was harshly critical of Peter Strzok, an FBI agent involved in the bureau's Clinton email and Russia investigations. He was later fired after the agency found that he had exchanged anti-Trump text messages with former FBI lawyer Lisa Page. But the inspector general report found no evidence "that these political views directly affected the specific investigative decisions that we reviewed."

Democrats on Friday grilled Comey's handling of the Clinton email probe and his decision to reopen the inquiry days before the 2016 elections . He defended his move, saying he haden't wanted want to conceal information that could impact a presidency, according to Rep. Sheila Jackson Lee, Democrat of Texas.

He was "consistent" in his comments about whether Trump had obstructed justice in firing him, she said. He has consistently stopped short of saying Trump obstructed justice.

Next year, Democrats may want him to return to Congress to publicly answer questions regarding obstruction of justice and impeachment. Comey said Friday he would "abide" a "responsible" request.

"I always want to respect the institution of Congress," said Comey. "I'd love it if they didn't want me to testify, but if they want me to testify and we can do it in a responsible way, I will abide it."

"We'll see what happens," he added.

Relationship to Barr

In a Post op-ed last year , Barr also criticized Comey's decision to announce the outcome of the FBI's investigation into Clinton's use of a private email server while secretary of state, rather than presenting his findings to a senior Department of Justice official.

Comey said Friday he liked and respected Barr, calling him a good attorney general candidate who will serve the department again well.

Comey said he was sure that Barr would talk to the appropriate career officials about how to handle the special counsel probe.

"I know he's an institutionalist who cares deeply about the integrity of the Justice Department, so I'm sure he'll use the standard career resources he has to judge what he should be involved in and what he shouldn't be involved in," said Comey.

Questions about Trump campaign, Clinton emails

Republicans tried to press Comey to divulge information about the FBI's efforts to surveil former Trump campaign adviser Carter Page as well as details about the genesis of the Russian investigation. But a Justice Department attorney seated next to Comey repeatedly said he would not be able to answer those questions, according to Rep. Darrell Issa, a Republican from California.

When asked at the news conference if a government lawyer shut down specific lines of questioning, Comey urged the public to check out the transcript when it is released.

"I think you will not see that happening," added Comey.

But when pressed on why he felt he could not answer certain questions, Comey said, "The FBI for understandable reasons doesn't want me talking about the details of the investigation that is still ongoing."

He added that that concerned a "very teeny part" of what was discussed Friday, while "a whole lot" of time was spent on Clinton's emails, "which will bore you."

Comey was also pressed by members about leaks that may have came from the US Attorney's office in the Southern District of New York to Rudy Giuliani. And he said he personally ordered an investigation into New York field agents and whether any leaks came from them, according to a source in the meeting. He said he didn't know if anyone was held accountable from that probe. Comey has previously said he ordered an IG investigation into apparent leaks in the Southern District of New York.

When asked why they did not want Comey to testify in public as he requested, North Carolina Republican Rep. Mark Meadows, who took part in the questioning, said they often discuss classified intelligence. "We would be giving him a pass that I don't think he deserves," added Meadows.

Before Comey gave his private testimony, Meadows said he had 14 pages of questions to ask Comey and that he expected the interview to go for several hours. He said Republicans felt it was important to call him in for questioning before Democrats took control of the House and committees' gavels next year.

"For us to just pack it up and go home is not what the American people deserve — and for the most part, it's not what they expect," Meadows said.

New York Rep. Jerry Nadler, the top Democrat on the House Judiciary Committee, called the panel's investigation into the FBI a "waste of time," and said he would end it when he becomes chairman next year. He added there wasn't evidence of political bias at the FBI.

This report has been updated with developments throughout Friday.