– Investigators into Russian meddling in the U.S. presidential elections are now also probing whether White House officials have engaged in a cover-up, according to members of Congress who were briefed Friday by Deputy Attorney General Rod Rosenstein.

That avenue of investigation was added in recent weeks after assertions by former FBI Director James Comey that President Donald Trump had tried to dissuade him from pressing an investigation into the actions of Trump's first national security adviser, retired Army Lt. Gen. Michael Flynn, members of Congress said, though it was not clear whom that part of the probe might target.

Even as members of Congress were mulling over the expansion of the case into possible cover-up, and its reclassification from counterintelligence to criminal, the scandal appeared to grow. The Washington Post reported Friday afternoon that federal investigators were looking at a senior White House official as a "significant person of interest." The article did not identify the official, though it noted that the person was "someone close to the president."

A person of interest is someone law enforcement identifies as relevant to an investigation but who has not been charged or arrested.

Coverups have traditionally been a major part of investigations that have threatened previous administrations. Articles of impeachment levied against Richard Nixon and Bill Clinton included allegations of obstruction of justice, as they were suspected of trying to hide other wrongdoing.

"This is a thorough investigation of what happened in the 2016 election, and it can go anywhere," said Rep. Mark Walker, R-N.C.

The possibility of a cover-up is the third branch of an investigation that began as a look at Russian meddling in the election and broadened into whether members of the Trump campaign had cooperated in that efforts, according to the briefing, members of Congress said.

The election interference aspect, which was first alleged in October in a report by the U.S. intelligence community, appears to be an accepted fact, said Rep. Elijah Cummings, D-Md., who has been at the center of some of the more explosive congressional revelations about the Russia probe. What's really left to be determined, he said, is whether there was "collusion with the Russians, and the possibility of an attempt to cover up."

The most visible questions about the possible cover-up have come since Trump took office, and especially in the days since the president abruptly fired Comey on May 9. News reports that Comey had written memos about his conversations with Trump since January have fueled that aspect of the probe.

On Friday, members of Congress said, Rosenstein clearly defined his role in Comey's dismissal, telling the assembly that while he had written a memo criticizing Comey's flouting of Justice Department rules for his public revelation of aspects of the Hillary Clinton e-mail probe, it was not intended as a justification for firing Comey. The members said he said he'd been told of the decision to fire Comey before he was asked to write the memo.

Rosenstein declined to discuss the timing of the memo and who had asked him to write it, saying the memo and its role in Comey's firing were likely to be part of the investigation, which will now be led by former FBI Director Robert Mueller, whom Rosenstein appointed special counsel on Wednesday.

"He refused to answer questions and he just kept off pushing everything onto Mueller," said Rep. Ruben Gallego, D-Ariz., who pronounced the briefing "useless."

Despite such frustrations, members agreed that Rosenstein had received a warm reception from both Republicans and Democrats at the meeting, a development that they said showed not only praise for his selection of Mueller to oversee the probe but also a recognition that Republican resistance to an independent probe was futile.

"Everybody applauded," said Rep. Emmanuel Cleaver, D-Mo. "Well, almost everybody. Let's say 95 percent applauded. Still, two weeks ago, that would not have happened."

Cleaver said Rosenstein's opening statement was "clear, concise" and had let those in the room know "this is a real investigation, looking into very real issues."

"I came out of there knowing that I trust this deputy attorney general, that I trust this special counsel and while he didn't answer many questions, he had a clear reason for not answering," Cleaver said.

Republicans were more reluctant to share details of the briefing, citing its classified nature, but they said they expected Congress to continue its own investigations.

House Majority Whip Steve Scalise, R-La., said clearly there might come a time when the special counsel thought the congressional investigation might interfere with his own probe. "But so far, there's been no suggestion that we can't move forward," he said.

House Majority Leader Kevin McCarthy, R-Calif., said one of his biggest takeaways was that Rosenstein had said he had no evidence that Comey had asked for more resources for the investigation before he was fired.

Rep. Dan Kildee, D-Mich., sounded a note of caution, fearing the public won't be told the investigation's results if it falls short of criminal charges.

"If the investigation determines that [cooperation between Trump's campaign and the Russians] happened but it doesn't rise to the level not only of criminality but a case that can be made, how will the public ever know about that? A decision to not charge doesn't necessarily give us any of that information," he said.