House intelligence committee Chairman Rep. Devin Nunes, R-Calif., is resisting growing calls for him to step aside over the revelation he had gone to the White House grounds to receive classified information related to committee’s investigation into Russian interference in last year’s election.

Speaking to reporters as he arrived on Capitol Hill Tuesday morning, Nunes said the investigation is “moving forward.”

“We’ve been investigating Russia for many, many years,” he said.

Asked if he felt he could continue to lead the investigation, Nunes replied: “Why would I not?”

His comments came amid a chorus of Democrats calling for his recusal.

“This is what a cover-up to a crime looks like,” Rep. Eric Swalwell, D-Calif., a member of the committee, said on MSNBC’s “Morning Joe.” “Going over to the White House, he went to receive information that you know, Joe, we can receive at the Capitol. We have our own secure facility.”

“I do think it is time for Mr. Nunes to step aside for the sake of this investigation,” Rep. Joseph Crowley. D-N.Y., said on CNN, “so we can get to the bottom of this without innuendo or suspicion.”

Related: Russia probe in turmoil as top Dem calls for Nunes’ recusal

Nunes sparked a firestorm last week when he declared that had seen information leading him to believe that communications from President Trump or his associates may have been “incidentally” picked up by U.S. intelligence agencies.

His statement, provided without evidence, was seized on by Trump, who said it supported his own apparently baseless claim that former President Barack Obama ordered a wiretap of his Trump Tower headquarters. The White House called on the House and Senate intelligence committees to investigate Trump’s wiretapping claim while they probe the Kremlin’s efforts to influence the U.S. election.

Nunes apologized to his committee members for briefing the White House on his findings before them, and intrigue has swirled as to who, exactly, gave the California lawmaker his secret intel. On Monday, reports indicated that he had talked to his mystery source on the White House grounds.

But it wasn’t just Democrats who were befuddled by Nunes’ actions.

“I think he put his objectivity in question at the very least,” Sen. Lindsey Graham, R-S.C., said on NBC’s “Today.” “The problem that he’s created is he’s gone off on a lark by himself, sort of an Inspector Clouseau investigation here.”

“I think there needs to be a lot of explaining to do,” Sen. John McCain, R-Ariz., said on “CBS This Morning.” “I’ve been around for quite a while, and I’ve never heard of any such thing.”

Graham said if Nunes is “not willing to tell the Democrats and the Republicans on the committee who he met with and what he was told, then I think he’s lost his ability to lead.”

McCain reiterated his call for a select committee to investigate Moscow’s meddling in the U.S. election process.

“This is a very serious issue,” McCain said. “It all started with Russian interference, attempt to change the outcome of our election. It turned into a centipede like these things have a tendency of doing, and another shoe seems to drop every few days.”

On Monday night, Rep. Adam Schiff, D-Calif., the ranking Democrat on the committee, called for Nunes to recuse himself.

Also read: Schiff has gone up against Russia (and Colbert) before

“This is not a recommendation I make lightly,” Schiff said in a statement. “But in much the same way that the attorney general was forced to recuse himself from the Russia investigation after failing to inform the Senate of his meetings with Russian officials, I believe the public cannot have the necessary confidence that matters involving the president’s campaign or transition team can be objectively investigated or overseen by the chairman.”

Nunes abruptly canceled a public hearing set for Tuesday, and CNN reported that all intelligence committee meetings were canceled this week amid the growing rancor within its ranks.

“I don’t trust him,” Rep. Jackie Speier, D-Calif., said on CNN. “I think he’s a very nice man. I think he is frankly over his head.”

“I think that the writing is on the wall,” she added. “It might make a good spy novel. It doesn’t make a good investigation.”

“Not only has this investigation sort of had a shadow cast on it, but the committee’s been put into suspended animation,” Rep. Jim Himes, D-Conn., said on “Morning Joe.”