
By Nicholas Fandos and Katie Benner
WASHINGTON — Since Republicans on the House Intelligence Committee declared that they had found no evidence of coordination between Russia’s election interference and the Trump campaign, its chairman has decisively turned the panel’s attention from investigation to investigators.
The chairman, Representative Devin Nunes of California, has issued increasingly bold demands for access to some of the Justice Department’s most sensitive case files. He has courted a series of escalating confrontations over access to materials that are usually off limits to Congress under department policy. And when those efforts failed, he threatened top law enforcement officials — mostly Republicans appointed by Mr. Trump.
In the latest episode, splashed across cable news this past week, Mr. Nunes demanded more documents and related materials for his investigation into allegations of surveillance abuse by federal law enforcement officials. His claim pitted him against not just the Justice Department, but also officials in the F.B.I., the intelligence community and the White House, who warned that disclosure could endanger a longtime source who is aiding the special counsel’s investigation.
As Mr. Nunes sees it, the cycle of confrontation is part of a legitimate effort by him and other House Republicans to conduct oversight of obstinate law enforcement officials.
But increasingly, top officials at the Justice Department have privately expressed concern that the lawmakers are simply mining government secrets for information they can weaponize against those investigating the president, including the special counsel, Robert S. Mueller III.
Mr. Nunes was unconvinced by the warnings about the intelligence and law enforcement source, first issuing a subpoena ordering that the Justice Department comply with his latest records request and then a pointed threat to hold Attorney General Jeff Sessions — who is not involved in the case — in contempt of Congress.
“Look, I just don’t believe that the White House does not want them to comply with a subpoena from Congress,” Mr. Nunes told reporters. “Everything else that has come out about this investigation has been pretty damaging to their activities,” he added, referring to the Justice Department.
The relationship between the Justice Department and Mr. Nunes has so eroded that when he trekked down Pennsylvania Avenue on Thursday from the Capitol to the department to discuss his latest request, Representative Trey Gowdy of South Carolina, a Republican colleague and former federal prosecutor, tagged along at the encouragement of the House speaker to help keep the meeting civil, according to a person familiar with the matter.
Democrats believe the pattern is clear: Mr. Nunes is abusing his authority to undermine the Russia investigation.
“The goal is not the information,” said Representative Adam B. Schiff of California, the top Democrat on the committee. “The goal is the fight. And the ultimate objective is to undermine the Justice Department, undermine Bob Mueller and give the president a pretext to fire people.”
The requests have also sent waves of tension through the department itself. The F.B.I. is generally opposed to giving lawmakers access to any materials related to a continuing investigation. But Rod J. Rosenstein, the deputy attorney general, who is overseeing the Russia investigation, has political considerations to weigh. To completely withhold information could be politically untenable — and potentially put the Mueller investigation at risk — given the support Mr. Nunes enjoys from Mr. Trump.
After months of giving into requests, Mr. Rosenstein has signaled that he is unwilling to go much further.
“If we were to just open our doors to allow Congress to come and rummage through the files, that would be a serious infringement on the separation of powers,” Mr. Rosenstein said at an event this month, amid reports that another House Republican had drafted articles of impeachment against him.
For now, tensions between Mr. Nunes and Mr. Rosenstein appear to have eased somewhat after Thursday’s briefings, which included both classified and unclassified sessions. The department did not share the requested documents with lawmakers, but it convened officials from the F.B.I. and Office of the Director of National Intelligence to lay out their case.
Afterward, Mr. Nunes and Mr. Gowdy said in a statement that they “had a productive discussion” and that they “look forward to continuing our dialogue next week.” Both sides signaled that they left with the impression that they had gotten the upper hand.
But the distrust, built over months of interactions, current and former officials said, is unlikely to dissipate soon.
The House speaker, Paul D. Ryan, has repeatedly and publicly backed Mr. Nunes. When Mr. Rosenstein and Christopher A. Wray, the F.B.I. director, came to Capitol Hill in January in a last-ditch effort to stave off an earlier subpoena, Mr. Ryan insisted that they comply and that Mr. Nunes would act responsibly. And when, weeks later, the department took rare public steps to try to block the release of a much-disputed memo drawn up by Republican committee aides from those documents, Mr. Ryan argued that Americans ought to be able to see the memo.
He offered similar support this time.
“This request is wholly appropriate,” Mr. Ryan told reporters on Thursday. “It’s completely within the scope of the investigation” by Mr. Nunes.
But Mr. Nunes’s handling of his secretive memo, released in early February, has been a source of lasting ill will. The document accused top F.B.I. and Justice Department officials, including Mr. Rosenstein, of abusing their authorities to spy on a former Trump campaign adviser suspected of being an agent of Russia. Law enforcement officials warned that the document was dangerously misleading and pointed out that Mr. Nunes had not read the underlying surveillance applications on which his four-page document was based.
Yet Mr. Trump seized on its findings to declare that he had been vindicated. And now, department officials said they were fearful that Mr. Nunes and his allies were seeking a repeat performance. More troubling, the officials said, is that Mr. Nunes’s actions suggest that he is more interested in courting conflict than understanding the case.
In the middle of another records dispute last month, Mr. Nunes threatened to hold Mr. Rosenstein in contempt or even try to impeach him if the Justice Department did not grant access to a nearly complete copy of a document used to open the Russia investigation in the summer of 2016, as well as material related to the wiretap of the Trump campaign aide, Carter Page. Mr. Rosenstein acquiesced and handed over the documents, but despite Mr. Nunes’s repeated demands, he never read them, according to an official familiar with the matter.
In another meeting, Mr. Rosenstein felt he was outright misled by Mr. Nunes’s staff. Mr. Rosenstein wanted to know whether Kashyap Patel, an investigator working for Mr. Nunes who was the primary author of the disputed memo, had traveled to London the previous summer to interview a former British spy who had compiled a salacious dossier about Mr. Trump, according to a former federal law enforcement official familiar with the interaction.
Mr. Patel was not forthcoming during the contentious meeting, the official said, and the conversation helped solidify Mr. Rosenstein’s belief that Mr. Nunes and other allies in Congress were not operating in good faith.
A spokesman for Mr. Nunes, Jack Langer, declined to comment.
Mr. Nunes made his newest request late last month. After consultation with the White House, the Office of the Director of National Intelligence, and the F.B.I., the Justice Department rejected it a few days later.
“Disclosure of responsive information to such requests can risk severe consequences, including potential loss of human lives, damage to relationships with valued international partners, compromise of ongoing criminal investigations, and interference with intelligence activities,” Stephen E. Boyd, an assistant attorney general, wrote in a letter to Mr. Nunes.
Since then, the two sides have been unable to agree on what Mr. Nunes wants to see. Mr. Nunes insists that he has never been interested in the sensitive source, but rather wants documents and other material related to his investigation into surveillance abuse allegations.
“I have never referenced an individual; they did,” he told reporters in recent days, referring to the Justice Department.
But at the department, the claim has been viewed as baffling. Mr. Nunes’s subpoena, they point out, refers to only one thing: a person.
Adam Goldman contributed reporting.