(CNN) The Justice Department inspector general found that former FBI Deputy Director Andrew McCabe "lacked candor" on four occasions when discussing the disclosure of information for a Wall Street Journal article about the FBI's Clinton Foundation investigation, according to a copy of the report obtained by CNN on Friday.

In addition, the inspector general determined that McCabe was not authorized to disclose the existence of the investigation because it was not within the department's "public interest" exception for disclosing ongoing investigations. The inspector general said that the disclosure to the Journal was made "in a manner designed to advance his personal interests at the expense of department leadership."

The instances the inspector general cited were McCabe's conversations with federal investigators and also with then-FBI Director James Comey in October 2016.

The report from Justice Department Inspector General Michael Horowitz, which was sent to Capitol Hill on Friday ahead of its expected public release, formed the basis of McCabe's firing last month by Attorney General Jeff Sessions.

Horowitz wrote in a letter to Senate Judiciary Chairman Chuck Grassley Friday he expected the report to be released in May, "absent any new additional developments."

President Donald Trump seized on the new report Friday to attack McCabe on Twitter, which he also did in the lead-up to McCabe's firing and immediately afterward.

"DOJ just issued the McCabe report - which is a total disaster," Trump tweeted Friday. "He LIED! LIED! LIED! McCabe was totally controlled by Comey - McCabe is Comey!! No collusion, all made up by this den of thieves and lowlifes!"

In a statement responding to the report, McCabe's attorney, Michael Bromwich, said the inspector general "utterly failed to support the decision to terminate Mr. McCabe."

"In written submissions to the OIG and DOJ, we demonstrated that the charges were unsupported by the evidence and that the OIG's conclusions and the FBI-OPR proposal to terminate Mr. McCabe were unjustified," Bromwich said.

The 35-page inspector general report goes into detail in arguing McCabe intentionally misled internal FBI and inspector general investigators about whether he had authorized the disclosure of an August 2016 phone conversation regarding the FBI's Clinton Foundation investigation to The Wall Street Journal. The report also says that McCabe told investigators he had informed Comey in October 2016 that he had authorized a discussion of the conversation, while Comey testified that he did not recall McCabe doing so.

"While the only direct evidence regarding this McCabe-Comey conversation were the recollections of the two participants, there is considerable circumstantial evidence and we concluded that the overwhelming weight of that evidence supported Comey's version of the conversation," the report states.

McCabe's attorney disputed that conclusion.

"Mr. McCabe's recollection of discussions he had with Director Comey about this issue is extremely clear; Director Comey's recollection is, by his own acknowledgment, not at all clear," Bromwich said. "And yet two of the lack of candor allegations are based on Director Comey's admittedly vague and uncertain recollection of those discussions."

McCabe's firing occurred less than two days before his planned retirement, denying him certain retirement benefits. The inspector general report on McCabe was forwarded to the FBI's Office of Professional Responsibility, which is staffed by career officials and recommended McCabe's dismissal.

McCabe responded to the firing by charging it was part of a larger effort from the Trump administration to discredit the FBI and special counsel Robert Mueller's investigation.

"This attack on my credibility is one part of a larger effort not just to slander me personally, but to taint the FBI, law enforcement, and intelligence professionals more generally," McCabe said in a statement last month.

Democrats have emphasized that McCabe's dismissal has nothing to do with the special counsel's investigation into Trump and Russia, while raising questions about the firing.

"The report issued by the Inspector General today has absolutely nothing to do with Special Counsel Mueller, Deputy Attorney General Rosenstein, the conduct of federal investigators so far, or the multiple indictments they have secured against Russian nationals and Trump campaign officials," Rep. Jerry Nadler, the top Democrat on the House Judiciary Committee, said in a statement.

Sen. Dianne Feinstein, the top Democrat on the Senate Judiciary Committee, said the rush to fire McCabe before his retirement "casts a tremendous shadow over the integrity of this process."

"I can't disregard his actions, but I'm disappointed the context wasn't given more weight," she said in a statement.

But Republicans say the report shows McCabe's firing was justified.

"The Inspector General found not only did McCabe divulge sensitive information, he did it without the permission, authority, or knowledge of his supervisor," said House Oversight Chairman Trey Gowdy. "This report continues to call into question decisions made by FBI leadership in 2016 and 2017, which is why the Oversight and Judiciary Committees will continue our joint investigation into the matter."

The report on McCabe is part of a larger investigation from Horowitz into the FBI's handling of the 2016 investigation into Hillary Clinton's email server.

That investigation is also expected to address the actions of Comey, whose upcoming book is already making waves and prompted Trump to call Comey a "weak and untruthful slime ball" in a tweet.

While the report is mostly focused on the disclosures in the Clinton Foundation investigation, it also sheds more light on his recusal in both the Clinton Foundation and Clinton email investigations.

The report states that Comey asked McCabe on October 27, 2016, to "drop off" a call about the Clinton emails found on former Rep. Anthony Weiner's laptop, one day before Comey informed Congress the FBI was reopening the probe due to the new emails.

McCabe was "very unhappy" about being forced off the call, according to the report. Comey wanted him off the call out of an "abundance of caution" because of "appearance issues" following a Wall Street Journal article about political donations to his wife from former Virginia Gov. Terry McAuliffe, an ally of Clinton.

On November 1, McCabe informed FBI officials he was recusing himself.

This story has been updated to include additional developments.