Right now, the main barrier standing in the way of Barr releasing Mueller’s report to Congress is the grand-jury material included in it, according to several Democratic staffers who spoke with reporters on Thursday on the condition of anonymity. Mueller empaneled a grand jury shortly after being appointed in May 2017. A grand jury hears testimony from witnesses, reviews evidence provided by the prosecutor, hears jury instructions that define the law, and then votes on whether a target should be indicted—as such, the grand-jury materials are key to understanding the full scope of the investigation. Federal rules of criminal procedure obligate Barr to redact the grand-jury material, although there have been instances where such material was released to Congress. The Watergate “Road Map,” for example, which was unsealed by the Washington, D.C., District Court in October, was written by the grand-jury foreman at the time specifically for Congress. It outlined the evidence the jury received over the course of the Watergate probe, but made no recommendation about the best course of action—only that it should “presently defer to the House of Representatives and allow the House to determine what action may be warranted at this time by this evidence.”

The House Democrats’ position now is that “there is nothing stopping Barr from giving us the grand-jury material” that informed Mueller’s findings, according to another Democratic staffer who spoke to reporters on Thursday on condition of anonymity to discuss internal deliberations. “If he doesn’t, then that amounts to a cover-up,” the staffer said.