(CNN) President Donald Trump's longtime confidante Roger Stone accused lawmakers of making "falsehoods, misstatements, and misimpressions" with allegations of collusion between the Trump campaign and Russian officials during his appearance before a congressional panel on Tuesday.

Stone, a one-time adviser to Trump, issued a combative opening statement Monday evening ahead of his highly anticipated appearance before the House intelligence committee Tuesday morning in a closed session.

Following his meeting, Stone said he had a "frank exchange" and described the preceding as "an entirely political exercise."

Stone said he denied any Russian collusion or knowledge of the hacking of John Podesta's email during the roughly three-hour closed-door session.

In his testimony, Stone attacked the very lawmakers questioning him, calling out the statements of three Democrats on the panel, including ranking member Adam Schiff of California.

"Multiple members of this committee have made false allegations against me in public session in order to ensure that these bogus charges received maximum media coverage," Stone said in his statement. "Now, however, you deny me the opportunity to respond to these charges in the same open forum. This is cowardice."

Stone said there were "partisan clashes" during the session — and he wasn't holding his breath for apologies he sought from the panel's Democrats — but he said that members were professional and courteous and he was prepared for all the questions asked.

Stone said he did not answer one question that was asked about his "intermediary" to WikiLeaks founder Julian Assange. Stone said that it was an off-the-record conversation with a journalist, though he added he would ask the journalist to release him from the off-the-record agreement.

Schiff said after the hearing there was one area of Stone's testimony where Stone would not answer questions, and that if Stone did not cooperate the committee would need to subpoena him. Schiff wouldn't say what the area was, though it had to do with Stone's description of his intermediary.

Rep. Mike Conaway of Texas, the Republican leading the panel's Russian investigation, said he agreed with Schiff that the committee needed to get the information about the intermediary from Stone.

He also told reporters that Stone's comments to the media describing the hearing were "accurate."

Stone's meeting comes after he battled with the committee when he demanded a public hearing, which lawmakers rejected, and as the members demanded he produce public records about his contacts with Russians, which sources said he did not do.

Multiple sources told CNN that Stone did not provide the committee with records about his alleged contacts with Russians, despite the panel's request. But one source familiar with the matter said that the committee asked for all public records -- and all of Stone's contacts with Russians have been released on Twitter and elsewhere. Stone had no private communications with Russians, the source said.

"We fully complied with the document request from the House on a timely basis," said Stone's attorney, Grant Smith.

In his 47-page opening statement, which includes exhibits, Stone denied he had any collusion with the Russian state, and also says that allegations Russia was responsible for the hacking of the Democratic National Committee were unproven.

"I understand the committee's interest in me, I use all clauses of the 1st Amendment to achieve my goals, I am out there, I am provocative and partisan, but let's be clear: I have no involvement in the alleged activities that are within the publicly stated scope of this committee's investigation -- collusion with the Russian state to affect the outcome of the 2016 election," Stone says.

Stone's testimony Tuesday is his first before the congressional panels investigating Russian election meddling and potential collusion with the Trump team.

Stone's own words have turned him into a lightning rod when it comes to the Russia investigation.

He admits exchanging private messages last summer with the Twitter handle belonging to Guccifer 2.0, who had already leaked stolen documents from the Democratic National Committee. At one point, Guccifer 2.0 told Stone, "tell me if I can help u anyhow," though Stone didn't appear to accept the offer.

The US intelligence community now believes Guccifer 2.0 was a front for Russian operatives involved in the Kremlin's election-meddling campaign, an assessment first publicly revealed in January.

During the presidential campaign last summer, Stone seemed to predict on a few occasions that WikiLeaks would soon release damaging information about Democratic presidential nominee Hillary Clinton. He specifically alluded to Clinton campaign chairman John Podesta and said on a few occasions that he was in engaged in back-channel communications with WikiLeaks founder Julian Assange, which Assange has denied.

Weeks later, WikiLeaks started releasing Podesta's emails -- which the US intelligence community says were stolen by Russia and handed over to the website. Stone has denied he had any advance knowledge of the Podesta email release, saying he was referring to his own research into Podesta. In his opening statement, Stone said he did not predict the hacking of Podesta's emails and that it's unproven Gufficer 2.0 is "a Russian cut-out."

"I posted this at a time that my boyhood friend and colleague, Paul Manafort, had just resigned from the Trump campaign over allegations regarding his business activities in Ukraine," Stone said in the statement. "I thought it manifestly unfair that John Podesta not be held to the same standard."

Lawmakers will likely be interested to learn more about who connected Stone with Assange, who has been under scrutiny by the FBI for some time, pertaining to past leaks of classified US material.

"We want to obviously understand the nature of his relationship with Guccifer, what he knew about the release of information," said Rep. Jim Himes, a Connecticut Democrat. "He predicted certain releases, so we're going to really want to understand the nature of that relationship and how broadly that relationship extended."

Rep. Mike Quigley, an Illinois Democrat, said Stone's comments predicting it would be Podesta's "time in the barrel" don't add up to his explanation that he didn't know the email leak was coming.

"It defies comprehension and belief all these things could have happened circumstantially," Quigley said. "I'd like to see copies of his social media contacts and his phone records. He needs to say under oath that he never emailed, texted or otherwise communicated."

One lawmaker on the panel, who requested anonymity to discuss the closed-door hearing, said some panel members see Stone as the key cog to the collusion allegations, and Democrats have wanted to talk to him for months now.

The lawmaker had hoped Stone's hearing would be held in public, in part due to the likelihood there would be competing narratives about what was said.

"He doesn't have access to classified information, so it's not like that part of the hearing shouldn't be open, I think, because again, he's not going to talk about classified or state secrets."

Stone first volunteered to testify in March, and his initial date in July was postponed. Stone said he's asked the committee to immediately release a transcript from the closed-door session.

"I have again asked for immediate release of the transcripts so that there will be no confusion or misinformation about my testimony," Stone said in a statement earlier this month.

Lawmakers want to hear testimony of potential eyewitnesses in classified settings because they say doing so publicly could undermine their investigation by tipping off other major witnesses.

Stone is one of a number of officials with ties to Trump that the committee is investigating as one of several congressional panels probing Russia's election meddling and possible collusion.

More recently, Stone has showcased his disdain for the US intelligence community, which he calls the "deep state," by publicly dismissing their conclusions about Russian interference in the 2016 election.

He even spread conspiracy theories about the leaked DNC emails, which were published by WikiLeaks during the Democratic convention last July. Stone claimed that a DNC staffer, who was later murdered, was responsible for the leak. No evidence has ever surfaced to back up this claim and the US intelligence community believes Russia was behind the DNC hacks and gave the emails to WikiLeaks.

Stone denies participating in any collusion with the Russian government and says he is a target of the American "deep state." He says his only link to Russia is that he enjoys drinking Russian vodka.