WASHINGTON (AP) — The White House refused to say on Thursday whether it secretly fed intelligence reports to a top Republican investigating possible coordination between Russia and the 2016 Trump campaign. Fending off growing criticism, the administration invited lawmakers from both parties to view classified material it said relates to surveillance of the president's associates.

The White House's invitation letter to lawmakers came amid a quickly rising storm over Rep. Devin Nunes, who heads the House intelligence committee. The New York Times reported that two White House officials — including an aide whose job was recently saved by President Donald Trump — secretly helped Nunes examine intelligence information last week.

The House panel's work has been deeply, and perhaps irreparably, undermined by Nunes' apparent coordination with the White House. He told reporters last week that he had seen troubling information about the improper distribution of Trump associates' intercepted communications, and he briefed the president on the material, all before informing Rep. Adam Schiff, the committee's top Democrat.

Speaking to reporters on Capitol Hill Thursday, Schiff said he was "more than willing" to come to the White House to view the new materials. But he raised concerns that the White House may have provided the information to his Republican counterpart first, and if so, why.

"If that was designed to hide the origin of the materials, that raises profound questions about just what the White House is doing," Schiff said. He vowed that the matter would not distract from the investigations into Russia's election meddling, saying, "if that's the objective here, it will not be successful."

Trump spokesman Sean Spicer said Thursday the material the White House wants the House and Senate intelligence leaders to view was discovered by the National Security Council through the course of regular business. He would not say whether it was the same material Nunes had already seen.

The Times reported that Ezra Cohen-Watnick, the senior director for intelligence at the NSC, and Michael Ellis, a White House lawyer who previously worked on the House intelligence committee, played a role in helping Nunes view the materials.

Cohen-Watnick is among about a dozen White House officials who would have access to the types of classified information Nunes says he viewed, according to current and former U.S. officials. He's become a controversial figure in intelligence circles, but Trump decided to keep him on over the objections of the CIA, according to the officials. They spoke only on condition of anonymity because they were not authorized to discuss the internal matter.

Cohen-Watnick and Nunes both served on the Trump transition team.