Mr. Ratcliffe visited Langley at least once, in August, to open the lockbox and read the Republican documents, according to three people familiar with his visit.
He most likely already had a road map to its contents. A number of Republican veterans of the Intelligence Committee staff now work in senior jobs in his office and on the National Security Council staff. Some would have been certain to know at least the broad outlines of the documents.
And Mr. Ratcliffe wrote in June to the committee to announce that he was doing a declassification review and seeking an unredacted copy of the 2018 report. In a letter 10 days later acquiescing to the request, Representative Adam B. Schiff, Democrat of California and the panel’s chairman, cautioned that the Republican report “sought to whitewash” Russia’s election interference and warned Mr. Ratcliffe against resuscitating “this misleading attack.”
Weeks later, in early August, Mr. Ratcliffe’s office sought, and received, permission from the committee to read the secret documents and annexes related to the report and stored at the C.I.A., said a person briefed on the request. Democrats have still not seen the documents themselves: Republicans are blocking Democrats on the panel from seeing them.
The Democrats on the House committee would most likely object to the release of all or part of the documents, leaving Mr. Ratcliffe the option instead of declassifying the underlying intelligence.
Mr. Ratcliffe, current and former intelligence officials said, endangers the agencies’ intelligence collection network with his aggressive declassifications by risking the exposure of C.I.A. sources and National Security Agency methods of intelligence gathering. A memo he declassified on Tuesday, for example, could give Russian intelligence important clues about how the C.I.A. gathered information in 2016, according to two people familiar with the intelligence.
Presidents and their senior officials rely on intelligence to make decisions about sending troops into battle, dismantling terrorist plots and other national security issues. It is supposed to be based on facts, and intelligence professionals believe that if politics color their assessments, they are less reliable.