WASHINGTON — Matthew G. Whitaker, the acting attorney general, announced on Monday that the special counsel, Robert S. Mueller, is wrapping up his investigation of Russian interference in the 2016 presidential campaign and whether the Trump campaign cooperated with Moscow’s operation.
“The investigation is, I think, close to being completed, and I hope that we can get the report from Director Mueller as soon as possible,” Mr. Whitaker said.
His impromptu remark, at the end of a news conference about an unrelated case, was a highly unusual confirmation of the state of the special counsel’s investigation. Justice Department policy ordinarily prohibits public comment on open criminal inquiries, and Mr. Mueller has refused to publicly discuss the case since he took over the investigation in May 2017.
Mr. Whitaker, who is considered intensely loyal to President Trump, took over the Justice Department late last year after the president forced Jeff Sessions to resign as attorney general.
Mr. Whitaker said he has been “fully briefed on the investigation” and that he looks forward to Mr. Mueller delivering his report.
A spokesman for Mr. Mueller declined to comment. Senior law enforcement officials have suggested that the inquiry was nearing its final stages and expected to wrap up in the coming weeks or months.
But Friday’s indictment of Roger J. Stone Jr., a longtime adviser to President Trump, raised the possibility of new evidence that might link the Trump campaign to WikiLeaks, the Russian government’s chosen repository for documents it stole from Democratic computers.
When F.B.I. agents arrested Mr. Stone at his home on charges of lying to Congress, witness tampering and obstruction of justice, they also searched for possible evidence to support those charges. His nearby recording studio was also raided, as was another home of his in Harlem, where agents carried out hard drives and other potential evidence.
Prosecutors typically shy away from discussing the progress of investigations to avoid unfairly framing public expectations, particularly if new evidence should unexpectedly arise. Before he announced that Mr. Mueller’s work was nearly finished, Mr. Whitaker said, “I am really not going to talk about an open and ongoing investigation.”
Under Justice Department regulations, Mr. Mueller is required to give the attorney general “a confidential report” explaining his prosecutorial decisions when he has finished his investigation. The attorney general, in turn, must send a report to Congress explaining why the work has concluded, though that can be simply a brief summary.
At his confirmation hearing, William P. Barr said he needed to learn more about the regulations before deciding what to do about disclosing Mr. Mueller’s findings.