Embattled FBI agent Peter Strzok spent more than 11 hours behind closed doors with House Republicans and Democrats Wednesday, fielding questions in both classified and unclassified settings about his personal political opinions and any impact they might've had on the Hillary Clinton email and Russia investigations. Top Republicans, including the president, have called for his firing and imprisonment.

Republicans, who demanded Strzok's appearance with a subpoena despite his willingness to appear voluntarily, were frustrated by Strzok's refusal to answer questions at several points at the advice of FBI counsel, and said they planned to question him again in a public hearing soon.

While the Justice Department's inspector general found no "documentary or testimonial evidence" that political bias impacted the Clinton email investigation that Strzok supervised, Rep. Mark Meadows, R-N.C., told reporters he "remained unconvinced that political bias did not have a factor in some of the decisions."

"I don't know that you can make the same conclusion on the Russia investigation," Meadows said of the IG's determination about Strzok's actions.

Privately, Strzok was critical of then-candidate Donald Trump and other political figures in text messages to a colleague with whom he was reported to be having an extramarital affair, telling her they would "stop" a Trump presidency in one of the thousands of messages they exchanged in 2015 and 2016.

Democrats were dismissive of the daylong interview, and claimed Republicans were working to undermine the Justice Department and special counsel Robert Mueller's investigation.

"This is an effort to try to shine some negative light on what special counsel Mueller is doing," Rep. Elijah Cummings, D-Md., told reporters.

Cummings, in a joint statement with Rep. Jerry Nadler, D-N.Y., the top Democrat on the House Judiciary Committee, called on the chairmen of the House Judiciary and Oversight Committees to release the full transcript of the unclassified interview with Strzok.

"Mr. Strzok's testimony is consistent with everything we already knew about the FBI’s handling of the Clinton investigation and the early stages of the Russia investigation," they said in a statement. "We call on Chairmen Goodlatte and Gowdy to immediately release the unclassified transcript of today’s interview and of every other interview conducted during this investigation. Let the public see how little they have to show for this partisan fishing expedition."

Republicans will further escalate tensions with the Justice Department on Thursday by taking up a resolution demanding DOJ compliance with several House Republican subpoenas for documents related to the 2016 campaign investigations. Deputy Attorney General Rod Rosenstein and FBI Director Chris Wray will also testify before the House Judiciary Committee on the IG report, and will likely face questions about the Russia probe.

Strzok was one of the FBI’s top investigators, a veteran assigned to lead the secretive investigation into alleged ties between the Trump campaign and Russia, after running the sensitive daily operations of the Hillary Clinton email probe.

Strzok arrived on Capitol Hill around 10 a.m. on Wednesday, ignoring questions from reporters as he entered the committee chambers.

Mueller quietly fired Strzok from his team last summer after discovering that he had sent politically charged and potentially anti-Trump text messages to FBI lawyer Lisa Page, with whom he was having the extramarital affair.

The Justice Department inspector general's report reviewing the FBI’s handling of the Clinton email probe concluded that Strzok’s text messages with Page "cast a cloud" over the FBI’s handling of the investigation and its credibility.

Page told the inspector general's investigators the two texted each other on work phones to keep their affair from their spouses.

Republicans on Capitol Hill point to Strzok’s messages about Trump as evidence to support their concerns about anti-Trump political bias at the Justice Department and FBI, while Trump and his legal team have said the exchanges and the report itself discredit the Mueller investigation.

“If you read the IG report, I’ve been totally exonerated,” Trump told reporters earlier this month at the White House. “I think that the Mueller investigation has been totally discredited.”

(The report did not deal with the Mueller investigation into possible collusion between members of the Trump campaign and Russia, and DOJ inspector general Michael Horowitz later told Congress “we don’t address issues with regard to the special counsel” in the review.)

Strzok told IG investigators that his personal political opinions “never transited into the official realm,” and that his message about stopping Trump was meant to reassure Page and not to suggest that he would affect the investigation.

Strzok, who was moved to the FBI’s human resources division, was escorted out of the FBI building last week as part of ongoing internal proceedings, his lawyer told reporters.

"Pete has steadfastly played by the rules and respected the process, and yet he continues to be the target of unfounded personal attacks, political games and inappropriate information leaks," Strzok lawyer Aitan Goelman said after the release of the IG report and calls from Trump lawyer Rudy Giuliani for Strzok to be imprisoned.

"Instead of publicly calling for a long-serving FBI agent to be summarily fired, politicians should allow the disciplinary process to play out free from political pressure."

Rep. Jamie Raskin, D-Md., a member of the House Judiciary Committee, called Strzok’s appearance an “irrelevant distraction,” in light of the inspector general’s conclusions.

"There are tens of thousands of criminal investigations in America every year. We do not perform heart or brain surgery on the investigators and prosecutors to determine whether they had a private political bias after it’s all over," he said. "The only relevant question is whether there is any official bias in the investigation, and there hasn’t been any and there’s been none credibly alleged."

Democrats on the House Intelligence Committee are also seeking to question Strzok as part of their unilateral efforts to continue the committee’s Russia investigation.

Before the interview, Trump Tuesday tweeted that the questioning of Strzok “should be shown to the public on live television, not a closed-door hearing that nobody will see.”

Goodlatte, the Judiciary Committee chairman who subpoenaed Strzok to appear before Congress this week, said he plans to bring Strzok back for a public hearing.

"I think he wants to tell his story," Goodlatte said on Fox News Sunday. "We want to hear it. If he's trying to claim that he's a victim in this process somehow, we have a lot of questions for him about that, too.

"But the fact of the matter is, he is a central figure in both of these investigations. He has a lot of information that it's very important that he share with the American people."

ABC News' Ali Dukakis contributed to this report.