Justice Department Inspector General Michael Horowitz, who opened the review last year, told congressional committee heads in the late-June letter that his investigators were still pursuing additional witness interviews but that much of the report has already been drafted and their investigative work is “nearing completion.”
The report is expected to be finished in late summer or early fall, an official briefed on the matter said.
On Monday, Trump called the Mueller investigation “fundamentally illegal” and a “total scam” in a tweet.
Attorney General Bill Barr, who has voiced his own concerns with the origins of the Russia investigation, had told a congressional panel earlier this year that he expected the inspector general report to be completed by May or June. But reports are often delayed as investigators try to complete their work and conduct follow-up interviews with witnesses.
Drafts or portions of the report are usually shared with witnesses to get responses before the report is made final. Key witnesses so far haven’t seen drafts or portions relevant to their testimony, according to lawyers representing them.
Horowitz told lawmakers last month that they have received and reviewed more than 1 million records but added that the review “has been complicated” by factors including “the current classification level of virtually all of the information we have obtained.”
A spokesman for the Office of the Inspector General declined to comment on the report’s timeline for completion or the contents of the Horowitz letter, which was provided to CNN by a congressional source.
The report is expected to center on a series of warrants that the FBI filed with the Foreign Intelligence Surveillance Court as they sought to investigate Page, who served as a foreign policy adviser on the Trump campaign, beginning in 2016.
The warrants were signed by top Justice Department officials, including former Deputy Attorney General Rod Rosenstein, and stated that the FBI believed that Page “has been collaborating and conspiring with the Russian government,” according to redacted copies released last year by the FBI.
Republicans have accused the FBI of political bias for withholding information about the evidence they used to underpin those requests, which included intelligence gathered by Steele, a former British spy, in an effort that was funded at a time by the Democratic National Committee and Hillary Clinton’s presidential campaign.
On Tuesday, Reuters reported that Steele was interviewed in London by three attorneys from the inspector general’s office in early June.
The intelligence reports that he assembled in the run-up to the 2016 election included claims that Page discussed energy cooperation and compromising information about Trump and Clinton with Russians in high-level meetings in that country in 2016, while he was still advising the Trump campaign.
The allegations were included in the surveillance applications, although they have never been publicly verified and Page has denied them. Page did however admit to other meetings with prominent Russians in congressional testimony.
Steele was also interviewed twice by investigators from Mueller’s office, and provided written testimony to the Senate Intelligence Committee last year — cooperation that has cost him more than $100,000 in legal fees, according to a person familiar with his London intelligence firm.
The inspector general investigation has unfolded alongside a second review initiated by Barr this year into the beginnings of the Russia investigation. That review, being led by John Durham, the US attorney for Connecticut, is also scrutinizing questions of political surveillance and is being assisted by intelligence leaders from the CIA, FBI and the Office of the Director of National Intelligence.
In an interview with the New York Times on Monday, Barr said that his “initial impression” from the ongoing review was that the Justice Department should tighten protocol around counterintelligence investigations into political candidates.
The attorney general has been criticized by Democrats as he’s offered windows into the reviews with commentary that mirrors Republican skepticism of the federal investigators’ tactics.
Testifying before Congress in April, Barr referred to the 2016 FBI surveillance as “spying,” and he told Fox News in May that some of the explanations he’s received so far “don’t hang together.”
Rosenstein, who appointed Mueller to take over the FBI’s Russia investigation in 2017, said in May that based on what he knew in 2017, the FBI’s investigation into Russian election interference was “justified.”
CNN’s Nina Dos Santos contributed to this report.