The almost 400-page report is the most anticipated political report in the last 20 years as both Republicans and Democrats scramble to defend or attack President Trump in the wake of its release.
House Democrats have already made formal requests to see the entirety of the report, and have floated taking the Justice Department to court over full disclosure of its contents and the underlying evidence.
In a four-page letter to Congress, Barr said in March that Mueller "did not find that the Trump campaign or anyone associated with it conspired or coordinated with Russian Federation in its efforts to influence the 2016 U.S. presidential election". Two days later, Barr summarized Mueller's conclusions in a four-page letter.
Justice Department regulations give Barr, a Trump appointee and the top US law enforcement officer, broad authority to decide what to release and what to withhold from the report. But he has said he must redact some sensitive information, including grand jury information and details about United States intelligence gathering.More news: Facebook To Bring Back Chat Feature Into Its Main App
The redactions in the report will be colour-coded by category, according to Barr, explaining the reasons that parts are blacked out. Barr noted in his summary that while Mueller's report "does not conclude that the president committed a crime, it also does not exonerate him".
Since Barr released his letter, Trump has set his sights on the Federal Bureau of Investigation, and accused the Justice Department of improperly targeting his campaign. The attorney general told lawmakers he believed that spying on Trump's campaign did occur, and that he plans to investigate whether it was legally justified.
Barr testified on Capitol Hill last week that redactions were necessary in some instances so that intelligence sources or ongoing prosecutions would not be compromised.
This means full analysis of the report will come out on Friday.
"In other words, (Barr) thinks as a matter of law a president can't obstruct justice, which is a very wild theory to which most people do not agree", Nadler said.