Donald Trump said his lawyer Rudy Giuliani has begun work on a rebuttal to Special Counsel Robert Mueller’s anticipated report capping his investigation of Russian interference in the 2016 presidential election.

“Already 87 pages done, but obviously cannot complete until we see the final Witch Hunt Report,” Trump said Friday on Twitter.

The president earlier lashed out at Deputy Attorney General Rod Rosenstein as “totally conflicted” in a barrage of tweets only hours before Mueller is set to reveal new details of his investigation. Trump also lobbed fresh attacks at Mueller and his fellow investigators — who are probing whether Trump associates aided Russian attempts to sway the 2016 election — as well as at former U.S. intelligence and law enforcement officials.

While Rosenstein appointed Mueller and supervised his investigation, it’s now under the supervision of Acting Attorney General Matthew Whitaker, who Trump tapped last month after ousting Attorney General Jeff Sessions. Sessions had recused himself from Mueller’s probe, prompting tension with Trump.

The president’s latest broadside comes as Mueller’s team is set to reveal more information Friday on two fronts: a sentencing memo outlining the degree of cooperation that Trump’s former personal attorney Michael Cohen has given to prosecutors and a separate filing in the case of former campaign chairman Paul Manafort that could to shed new light on allegations that Manafort lied to Mueller’s team following his guilty plea.

In the weeks since November’s midterm elections, the Mueller team has been closing chapters on three figures central to the inquiry: Cohen, Manafort and onetime national security adviser Michael Flynn.

In a Dec. 4 filing in the case involving Flynn, prosecutors urged that Flynn receive no prison time in exchange for his cooperation.

Flynn pleaded guilty to lying to the FBI about contacts with former Russian Ambassador Sergey Kislyak and about his work on behalf of the Turkish government. The filing said Flynn had given Mueller’s team “firsthand insight” — and that his choice to cooperate “likely affected” the decisions of other witnesses to come forward.