Washington (CNN) Justice Department Inspector General Michael Horowitz's report into the FBI's handling of the Russia investigation will be released December 9, Senate Judiciary Chairman Lindsey Graham said Wednesday night.

"It will be December 9th, you'll get the report," the South Carolina Republican told Fox News. "That's locked."

What the report says is unknown. But some witnesses who have been interviewed by the inspector general say they expect that it will likely reveal some missteps, though none that should be interpreted as undermining a legitimate investigation.

The timing of the release, pronounced imminent for months, could be a boon for Republicans amid the unfolding impeachment proceedings.

Launched in early 2018, the inspector general investigation centered on a series of warrants the FBI filed with the Foreign Intelligence Surveillance Court as it sought to investigate Carter Page, a onetime foreign policy adviser to the 2016 Trump campaign.

The warrants -- signed by top Justice Department officials, including former FBI Director James Comey and former Deputy Attorney General Rod Rosenstein -- stated that the FBI believed Page "has been collaborating and conspiring with the Russian government," according to redacted copies the bureau released last year.

To bolster their request to the surveillance court, the FBI relied at times on claims about the 2016 Trump campaign collected in a dossier of unverified intelligence reports by former British spy Christopher Steele.

In recent weeks, President Donald Trump and his supporters have led a steady drumbeat of anticipation over the report, suggesting it will provide evidence of improper conduct by the FBI that undermines the credibility of the Russia investigation.

Investigators from the watchdog office reviewed more than 1 million records and conducted more than 100 interviews as part of the probe, and in recent weeks the Justice Department and FBI have pored over a draft of the report to determine the classification levels of the material, Horowitz has told lawmakers.

Horowitz will appear before the Senate Judiciary Committee on December 11 to discuss the findings of his report.