On Thursday California Senator Dianne Feinstein announced she had received a document concerning Supreme Court nominee Brett Kavanaugh and had forwarded the matter to the FBI. Democrats are calling for Feinstein to make the document public, but she has refused to do so citing a promise to keep a confidentiality agreement.

“I have received information from an individual concerning the nomination of Brett Kavanaugh to the Supreme Court,” Feinstein said in a statement. “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.”

Feinstein is the senior minority member on the Senate judiciary committee, which is in charge of holding hearings and investigating nominees to the Supreme Court.

The Intercept first reported the existence of the document on Wednesday. The content of the document is unclear, but it’s believed the document was given to Feinstein by one of her California constituents.

The Intercept reported different sources have told them different versions of the story in the document, but one consistent theme is that the document describes an encounter in high school between Kavanaugh and a female student.

Also according to the Intercept, the woman who is the subject of the document is now being represented by Debra Katz, a whistleblower attorney who works with #MeToo survivors. Katz’s firm has refused to comment on the matter.

Democrats are frustrated by Feinstein’s decision to keep the document private and want to view the document themselves so as to jointly decide whether the document be made public, and not leave that decision to Feinstein.