Trump adviser Roger Stone denies collusion with Russia In a statement, Stone said he had no prior knowledge of DNC email hacking.

 -- President Donald Trump's longtime confidant Roger Stone denied allegations of collusion with Russia during the presidential campaign, following a closed-door interview with the House Intelligence Committee on Tuesday.

"I expressed my view that I am aware of no evidence whatsoever of collusion of the Russian state with anyone in the Trump campaign, or anyone associated with Donald Trump," Stone told reporters after the three-hour-plus interview.

Stone said he answered all the panel's questions, except for one: the name of the intermediary he used to communicate with WikiLeaks and Julian Assange.

Now, top members of the committee are discussing whether to subpoena Stone for that information, which they see as crucial to their investigation into Russia efforts to influence the presidential race.

"The intermediary is a journalist and the conversation was off the record. I am not going to burn someone who I spoke to off the record," Stone said after the interview. He added that he would ask permission to share his contact's identity with the committee.

Adam Schiff, D-Calif., the panel's top Democrat, told reporters the committee could subpoena Stone if he doesn't "cooperate in the future," but declined to say which questions Stone failed to answer.

Calling a subpoena "premature," Rep. Mike Conaway, R-Texas, the Republican leading the investigation, told ABC News he wants to give Stone a chance to cooperate.

"If he can get that done in a relatively quick time-frame, turnaround, then we won’t need it," he said. "But if he can’t get that done I’ll discuss with Mr. Schiff what our next steps will be."

Stone said he had no prior knowledge about the hacking of Clinton campaign chairman John Podesta's email or the release of those emails by WikiLeaks, despite tweeting about Podesta's "time in the barrel" before the messages appeared online.

In a more than 40-page statement released before the interview, he also criticized members of the committee — including Adam Schiff of California, the panel's top Democrat, and Jackie Speier, another California Democrat — for making "provably false statements" about him.

"I will not let myself be a punching bag for people with ill intentions or political motives," he said.

Stone briefly held a formal role on Trump's presidential campaign. He has known Trump for 40 years and urged him to run for president for decades.

Arriving on Capitol Hill with his attorneys Tuesday morning, Stone told reporters he felt "excellent."

He said he planned to tell the committee "the truth, the whole truth and nothing but the truth."

Stone is among several former campaign operatives the House Intelligence Committee has sought to question. The panel has met with Podesta and Michael Caputo, a Trump adviser close to Stone.

The panel will also interview Boris Epshteyn, a former Trump campaign adviser, on Thursday.