Less than a day after The Intercept reported that Sen. Dianne Feinstein (D-Calif.) received a letter that purportedly details an "incident" involving Trump Supreme Court pick Brett Kavanaugh and "a woman while they were in high school," Feinstein announced in a statement on Thursday that she has referred the secret document to the FBI.

"I have received information from an individual concerning the nomination of Brett Kavanaugh to the Supreme Court," Feinstein said. "That individual strongly requested confidentiality, declined to come forward or press the matter further, and I have honored that decision. I have, however, referred the matter to federal investigative authorities."

"This matter has been referred to the FBI for investigation," Sen. Dick Durbin (D-Il.) told BuzzFeed when asked about the letter.

News that a letter about a judge who is up for a lifetime appointment to the nation's highest court has been sent to the FBI "seems like a pretty big deal," political analyst Matt McDermott noted in response to Feinstein's statement.

With a final vote on Kavanaugh's nomination set for next week, rumors regarding the contents of the letter have reportedly been swirling around Capitol Hill in recent days. Democrats on the Senate Judiciary Committee have requested to view the document, but Feinstein has refused to give her colleagues access.

According to The Intercept's Ryan Grim, "Different sources provided different accounts of the contents of the letter, and some of the sources said they themselves had heard different versions, but the one consistent theme was that it describes an incident involving Kavanaugh and a woman while they were in high school."

"The letter took a circuitous route to Feinstein," noted Grim, who reported that the document was "relayed to someone affiliated with Stanford University, who authored the letter and sent it to Rep. Anna Eshoo, a Democrat who represents the area."