Washington (CNN) A draft of the much-anticipated report from the Justice Department's internal watchdog, addressing a wide-ranging set of allegations that department protocols were flouted when the FBI investigated Hillary Clinton's handling of classified information, has been completed, according to sources with knowledge of the matter.

Inspector General Michael Horowitz informed lawmakers on Capitol Hill Wednesday that his office has provided leadership at the Justice Department and FBI with a copy of the draft report and has requested that they review it for classified information.

"We will update you on the specific timing for the report's release, and I will be prepared to provide a briefing and testify publicly about our findings and conclusions as soon as the report is released," Horowitz wrote in a letter to members of various committees.

Of all the politically charged reports accusing law enforcement of misconduct since President Donald Trump took office, this one from the Inspector General's office -- now 17 months in the making -- has the potential to deliver the stiffest blow for officials who formerly occupied the highest positions within the FBI and Justice Department.

"It's not going to be good, it's just a question of how bad it's going to be," said one former Justice Department official.

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