WASHINGTON — The Justice Department sought on Monday to tightly hem in this week’s congressional testimony by the former special counsel, Robert S. Mueller III, telling him in a letter that he “must remain within the boundaries” of the public version of his report on the Russia investigation.
The department also told Mr. Mueller that he could not “discuss the conduct of uncharged third parties,” like President Trump, his family and his closest associates, nor could he discuss “the redacted portions of the public version of your report.”
“Should you testify, the department understands that testimony regarding the work of the special counsel’s office will be governed by the terms you outlined on May 29,” the department said, referring to a rare public news conference by Mr. Mueller in which he said he would appear before lawmakers only reluctantly, and would not discuss any matters not contained in his 448-page report.
“The report is my testimony,” Mr. Mueller said then.
Mr. Mueller, 74, is scheduled to appear before the House Judiciary and Intelligence Committees on Wednesday to answer questions about his two-year inquiry into Russia’s plot to undermine the 2016 election and any links to Mr. Trump’s campaign, as well as about the president’s efforts to thwart the investigation.
While the report did not explicitly accuse the president of a crime, Mr. Mueller wrote that he could not clear him of one, either. “If we had confidence after a thorough investigation of the facts that the president clearly did not commit obstruction of justice, we would so state,” the report said.
The Justice Department cast Mr. Mueller’s testimony as unnecessary and said the former special counsel was being granted an unusual privilege in being allowed to present his findings to lawmakers.
“The department generally does not permit prosecutors such as you to appear and testify before Congress regarding their investigative and prosecutorial activity,” the letter said.
Attorney General William P. Barr has sought to play down large portions of the report that criticized the president and his campaign for accepting help from Russia and outlined multiple instances in which Mr. Trump tried to derail the special counsel’s inquiry.
In an interview this month with The New York Times, Mr. Barr said House Democrats were forcing Mr. Mueller to testify to “create some kind of public spectacle.” He also said that the notion that Mr. Trump worked with Russia to subvert the election was “bogus” and that law enforcement needed more stringent protocols around whether to investigate political candidates.
Lawmakers from both parties want to use Mr. Mueller’s work to support their assertions about Mr. Trump — with Republicans seeking to highlight that the president was not accused of any crimes and Democrats hoping that the testimony will bring to the public’s attention more of the report’s most damning information about how Mr. Trump has conducted himself in office.
Some Democrats also hope that the testimony will fuel public support to impeach the president.
In its letter to Mr. Mueller, the Justice Department highlighted his public statements vowing to discuss only those details from his investigation that were already in the public record. The department couched the letter as a response to his past remarks and said it agreed with Mr. Mueller’s assertion that he should “not go beyond our report.”
Given Mr. Mueller’s repeated assertions that he will not stray beyond the public version of his report, Democrats and Republicans do not expect the five hours or so of hearings to produce many shocking revelations.
But relatively few Americans have read the report, and Mr. Mueller could paint a more vivid and easier-to-understand narrative than that document’s dense, dry language provided.