In a letter dated March 15, Mr. Grassley asked N.Y.U. to provide details about Mr. Lew’s compensation and other loans the university had made since 2000, as well as related university policies. He requested a reply by March 29.

On that date, the university wrote that it was “N.Y.U.’s intention to voluntarily respond to your request, with sufficient information to enable you to evaluate the policy issues.” That letter included Form 990s — tax documents that nonprofit organizations must make public each year — and information about N.Y.U.’s bylaws and compensation policies. “We will be providing other materials in response to your request in the near future,” the document continued. “As you might imagine, it will take some time to supply information responsive to all of your questions.”

A second letter, dated April 19, included various policies and guidelines, summaries of two loan programs, redacted board of trustees and compensation committee minutes and, among other readings, a Wall Street Journal opinion article. “N.Y.U. is continuing to collect and process additional responsive materials,” the letter said. “We expect to be back to you very shortly about your requests concerning Secretary Lew.”

A few weeks later, N.Y.U. representatives brought documents relating to Mr. Lew’s loans over to the Dirksen Senate Office Building, where two members of Mr. Grassley’s staff reviewed them. But though they were allowed to take notes, they were not permitted to make copies or to keep any of the documents for further review. Then on June 28, the university provided the total number and size of loans that N.Y.U. has made to faculty members and executives, but not about any individual loans.