Justice Department officials are trying to release in the coming weeks a potentially explosive inspector general report about the FBI’s investigation into President Trump’s 2016 campaign, according to multiple people familiar with the effort.

One person involved in the discussions said the target date for the report’s release has been Nov. 20, but another indicated that the Justice Department is unlikely to deliver it by then and that it is more likely to come after Thanksgiving because of the complicated and contentious mix of legal, classification and political issues at play.

The report’s findings will mark a major public test of Attorney General William P. Barr’s credibility, given his past suggestions of significant problems with the investigative decisions made by former FBI leaders involved in the case.

The findings by Inspector General Michael Horowitz also will set the stage for the separate but related investigation led by U.S. Attorney John Durham, who is investigating how U.S. intelligence agencies pursued allegations that Russian agents might have conspired with Trump associates during the 2016 campaign. Officials have recently said that investigation is pursuing potential crimes.

Barr has spent weeks working on the declassification decisions, as Horowitz scrutinized large volumes of classified information to assess how the FBI launched and pursued the investigation and related cases, people familiar with the matter said. Like others, they spoke on the condition of anonymity because the report is not yet public.

But a number of key figures in the probe have yet to receive draft sections of the inspector general’s findings, suggesting that the public release is still at least a week away, according to people familiar with the matter. It is possible, too, that as draft language of the report is shared with different people, the entire process could become bogged down by disputes about the accuracy of certain passages.

Sen. Lindsey O. Graham (R-S.C.), chairman of the Senate Judiciary Committee, plans to meet Wednesday with Barr to talk about the report’s planned rollout, according to people familiar with the matter. The inspector general’s work is independent of the attorney general, but in this case, the two must work closely on the release because the inspector general does not have the authority to declassify information. Barr does. Horowitz is not expected to attend the meeting with Graham, these people said.

At an unrelated public appearance Tuesday, Horowitz declined to discuss the timing of his report. A spokeswoman for Barr also declined to comment.

In a letter to lawmakers last month, Horowitz wrote that the declassification process was “nearing completion.” The goal, Horowitz wrote, “is to make as much of our report public as possible. I anticipate that the final report will be released publicly with few redactions.”

Congressional Republicans have been pushing for the inspector general’s report to come out as quickly as possible, but they are also pressing Barr to declassify and make public as much information as possible — goals at odds with each other.

Republicans hope the report will give them ammunition to argue the FBI was corrupt in its pursuit of the president and his alleged ties to Russia, according to a person involved in the GOP discussions. Congressional Republicans have defended Trump amid the ongoing impeachment inquiry centered on his effort to convince Ukraine to investigate Democratic presidential candidate Joe Biden.

Trump’s supporters have long called for officials to “investigate the investigators,” and some GOP lawmakers have predicted the inspector general’s findings will prove their accusations that a “deep state” cabal of anti-Trump bureaucrats sought to thwart his presidency.

Barr, through public statements, has fueled some of those suspicions.

At an April congressional hearing, for instance, the attorney general declared the Trump campaign was spied on during the 2016 campaign, though aides later said he used that term not in a pejorative sense but in the more general meaning of surveillance.

“I think spying on a political campaign is a big deal,” Barr said. “I think spying did occur, but the question is whether it was adequately predicated and I’m not suggesting it wasn’t adequately predicated, but I need to explore that.”

At the same hearing, he criticized former leaders of the FBI, saying: “I think there was probably a failure among a group of leaders there in the upper echelon.”

To Barr’s critics, the inspector general’s report will mark a major test of his independence.

“The first question is whether the report shows any basis for Barr’s pretty aggressive implications that the Justice Department did something wrong in opening the [Trump] investigation,” said Matthew Miller, a former Justice Department spokesman during the Obama administration who has been highly critical of Barr.

If the report finds missteps by the FBI, “even minor ones, it will be used as a rhetorical tool for the president,” Miller said.

Current and former law enforcement officials have said the Russia investigation began in late July 2016 with an examination of George Papadopoulos, a Trump campaign adviser whose statements and behavior raised suspicions among diplomats and intelligence officials. After Trump fired FBI Director James B. Comey in May 2017, the Russia investigation was handed over to special counsel Robert S. Mueller III, who filed a lengthy two-volume report of his conclusions earlier this year, deciding there was no proof of a conspiracy between Trump associates and the Kremlin, and declining to reach a conclusion about whether the president obstructed justice. Barr examined Mueller’s evidence and concluded he had not.

The current and former officials insist the investigation was handled correctly and carefully, and argue it would have been a dereliction of duty on their part not to investigate alarming allegations that members of a presidential campaign were conspiring with a foreign power.

Republicans, however, have alleged that the FBI began looking at Trump associates before late July and that investigators relied on weak or phony evidence. Notably, they have accused FBI officials of placing too much faith in a dossier gathered by a former British intelligence officer whose sources claimed that Trump and some of those close to him were in thrall to Russian officials.

The FBI and Justice Department applied to the Foreign Intelligence Surveillance Court in October 2016 to monitor the communications of a former Trump campaign adviser, Carter Page. Those applications were reauthorized, and the surveillance continued into mid-2017. Horowitz examined whether those applications were handled properly.

Law enforcement officials close to the attorney general have said he is concerned also about how decisions were made in 2017 to open an investigation into then-Attorney General Jeff Sessions over his interactions with Russia’s ambassador to the United States.

Trump has called the FBI’s investigation “an attempted coup.”

Barr has said his principal concern is to make sure that whatever investigative steps were taken were justified.

“I believe there is a basis for my concern, but I’m not going to discuss the basis for my concern,” he said in April, adding that he did not understand why, if intelligence officials thought Russian figures posed a danger to a U.S. election, they did not warn the campaign about specific risks.

“If I were attorney general and that situation came up, I would say, ‘Yes, brief the target of the foreign espionage activity,’ ” Barr said.

In an interview with CBS weeks later, he went further.

“It’s a serious red line that’s been crossed. . . . These counterintelligence activities that were directed at the Trump campaign were not done in the normal course and not through the normal procedures as a far as I can tell,” Barr said. “Republics have fallen because of Praetorian Guard mentality where government officials get very arrogant, they identify the national interest with their own political preferences and they feel that anyone who has a different opinion, you know, is somehow an enemy of the state,” he said.

Jonathan Turley, a George Washington University law professor and longtime friend of Barr’s, said the attorney general’s approach to the inspector general’s work has been justified.

“There’s legitimate issues on both sides of the 2016 election that warranted investigation,” Turley said. “Barr has done precisely what he said he would do in his confirmation hearing — protect the investigations on both sides of the controversy. With Mueller, he fulfilled that. . . . I think Barr has been vindicated already as more of the record has been made public, it’s just that the vindication has not been recognized.”