Since Republicans began tormenting him almost two years ago over a botched gun-smuggling investigation, Attorney General Eric Holder has wielded it as a shield.

“It” is a forthcoming report from the Justice Department’s Office of the Inspector General on exactly what happened in Operation Fast and Furious, in which agents for the Bureau of Alcohol, Tobacco, Firearms and Explosives allowed hundreds of powerful assault guns to “walk” to criminal networks.

When facing down hostile GOP lawmakers in antagonistic Congressional hearings, or refusing to disclose subpoenaed documents, Holder has pointed to the report as evidence he wants to get to the bottom of the scandal.

“I am . the attorney general who called on an inspector general to look into this matter, to investigate this matter,” Holder said to Sen. John Cornyn (R-Texas), moments after Cornyn called on Holder to resign in a Senate Judiciary Committee hearing earlier this summer.

Now, Justice Department Inspector General Michael Horowitz’s report will be released imminently, posing a potential danger both to Holder and to his GOP nemesis, House Oversight and Government Reform Chairman Darrell Issa (R-Calif.).

By putting such emphasis on the report, Holder has elevated its importance, leaving him no room to complain about its findings if they reflect poorly on his or his top subordinates’ conduct.

But to the extent the report exonerates, or does not discuss, the role of Holder and key top lieutenants such as Assistant Attorney General Lanny Breuer, it could be used to dismiss any further inquires into their conduct.

GOP lawmakers have expressed come concern whether Horowitz has conducted a thorough or aggressive investigation. Reps. Trey Gowdy (R-S.C.) and Jason Chaffetz (R-Utah) met with him in July.

When Breuer, whose criminal division approved the Fast and Furious wiretaps, was up for confirmation in the Senate, Horowitz wrote a letter of support saying that based on knowing Breuer for “several years,” he would make an “outstanding leader” of the DOJ’s criminal division.

The two are said to be friends. A call to Horowitz’s office was not returned Friday.

In a Wednesday letter to Issa, Horowitz said a draft version of the report is in the hands of the DOJ officials whose conduct it concerns.

“Consistent with the longstanding practice of our Office, we have provided a copy of the OIG’s draft report to the Department of Justice (Department). We have also made arrangements to permit individuals whose conduct Is criticized in the draft report (and who also cooperated with our investigation) to review those portions of the report that relate to their conduct,” the letter said.

The DOJ is also reviewing the draft for information that the department would seek to redact for law enforcement purposes, Horowitz added.

“In addition, consistent with standard practice, given that our report may contain references to law enforcement sensitive information, Title III electronic surveillance information, sealed court records, and grand jury material, as well as information that may fall within the President’s assertion of Executive Privilege, we asked the Department to conduct a sensitivity review to determine whether it believes that any information contained in the report cannot be released publicly,” the letter said.

With the backdrop of GOP concern that the report would not thoroughly investigate the role of higher-ranking DOJ officials, Issa scheduled a hearing with Horowitz for Tuesday.

However, Horowitz said in the letter, the report might not be ready for release by then.

“I am pleased to make myself available to testify about the OIG report before the House Oversight and Government Reform Committee, or any other Congressional Committee that may request my testimony, once our report is final and we have publicly issued it. However, as of this date, I do not yet know the precise timing for the release of our report,” the letter said.

Issa might delay the hearing, GOP sources said, but as of Friday, it remained scheduled for Tuesday despite Horowitz’s letter.

While the report will cover topics that have been thoroughly investigated by Issa, Horowitz will have had access to tens of thousands of pages of documents that Holder refused to provide the Oversight committee.

And some questions still loom. Although a clear picture has emerged about what happened in Phoenix, where the Fast and Furious operation originated, the identity of the highest-ranking official who approved the tactics that were used remains unanswered.

In Fast and Furious, agents for the Bureau of Alcohol, Tobacco, Firearms and Explosives allowed assault guns to “walk,” which meant ending surveillance on weapons suspected to be en route to Mexican drug cartels.

The tactic, which was intended to allow agents to track criminal networks by finding the guns at crime scenes, has been roundly condemned after two guns that were part of the operation were found at Border Patrol agent Brian Terry’s murder scene.

After initially denying the tactic was ever used, the DOJ conceded it was but insisted senior officials were not aware of its use.