Staffers on the Senate committee told Fox News they also have expanded their investigation into whether presidential candidates were unmasked and information was misused - and what role former national security adviser Susan Rice, among others, played following reports that she requested Trump-affiliated names be unmasked.
Rice's supposed unmasking requests appeared to be "normal and appropriate" inquiries for a senior government official to make, another congressional source told CNN.
"I think it's going to be the biggest story", Trump said in an interview with the New York Times last week.
A Bloomberg report last week revealed Rice had unmasked the names of Trump associates who were swept up in US foreign surveillance.
"And another source said there's "absolutely" no smoking gun in the reports, urging the White House to declassify them to make clear there was nothing alarming in the documents", CNN reports.
He visited White House grounds the day before to view the information, and two White House officials reportedly helped give him the information. As national security adviser, Rice could only request that the names of USA persons be unmasked if identifying them was necessary to understanding the value of the intelligence.
The report casts fresh doubt on Trump's explosive and still baseless allegation that his predecessor ordered an illegal wiretap on Trump Tower during the campaign - as well as his insistence, citing no evidence, that Rice may have committed a crime. Rice may now be on the long list of witnesses the committees plan to interview.
GOP wins tight Kansas race in first House vote of Trump admin
On Tuesday, Thompson took nearly 46 percent of the vote-improving on the Democratic percentage from 2016 by more than 16 points. Estes took 53 percent of the vote to Democrat James Thompson's 46 percent in the race for Kansas' southern 4th District.
Still, some members of Congress continue to have concerns about the justification given for the unmasking requests and the standards for the intelligence community to grant such requests, which reveal the private data of U.S. persons mentioned in intelligence reports based on routine intelligence collection aimed at foreign nationals. However, Democrats on the committee have now seen the information that Nunes has, and no one denies that Rice is behind the unmasking.
On March 22, Nunes said that while there was no indication unlawful survaillance of Trump transition officials occurred, the reports in question were concerning to him because USA citizens' identities were revealed, or "unmasked", in them.
"Perhaps I didn't know how right I was", Trump said, "Because nobody knew the extent of it". "It's such an important story for our country and the world", he added, calling it, "truly one of the big stories of our time".
Rice told MSNBC that she was carrying out routine duties in making the requests, and did so to understand the "context" or "importance of the report".
But the House review has been thrown into turmoil after Nunes last month expressed alarm about the unmasking of United States persons, including Trump advisors, caught up in incidental collection.
Nunes' office has not responded to CNN's request for comment. That came from US officials who spoke to Eli Lake, although Trump himself seems sufficiently convinced that she was involved somehow to have suggested publicly that she might be guilty of a crime. That latter issue, eventually, forced Nunes to step aside from his committee's Russian Federation inquiry.