Chairman Darrell Issa (R-Calif.), questions Michael Horowitz, Inspector General of the Department of Justice, during a House Judiciary Committee hearing on Capitol Hill on Sept. 20. The committee is hearing testimony about the failures of Operation Fast and Furious. (Mark Wilson/GETTY IMAGES)

After an 18-month investigation that produced a 471-page report on the flawed “Fast and Furious” gun-tracking operation, Republican lawmakers told the ­Justice Department’s inspector general Thursday that senior Justice officials still need to be held accountable for the botched case.

During a three-hour hearing, Republicans on the House Government Reform and Oversight Committee praised the report released Wednesday by Inspector General Michael Horowitz as fair and comprehensive. Committee Chairman Darrell Issa (R-Calif.) called it a “huge step toward restoring public faith in the Justice Department.”

But the lawmakers criticized Justice officials for not imposing harsher penalties on the 14 officials whom Horowitz said should be considered for disciplinary action. During the hearing, they singled out Assistant Attorney General Lanny A. Breuer, who heads the department’s criminal division.

“We expect that all 14 would find a way to find appropriate new occupations,” Issa said.

In his report, Horowitz said his investigation “revealed a series of misguided strategies, tactics, errors in judgment and management failures that permeated ATF headquarters and the Phoenix Field Division, as well as the U.S. Attorney’s Office for the District of Arizona.”

The watchdog report concluded that Attorney General Eric H. Holder Jr. did not know about the tactics used in Fast and Furious until the operation was over. Beginning in 2004, ATF agents in Phoenix watched as gun-trafficking suspects bought hundreds of guns; the agents then let the guns “walk” so the agency could link them to a Mexican firearms-trafficking ring.

ATF only seized 100 of the weapons, losing track of about 2,000 guns, including AK-47 style rifles.

In his report, Horowitz said he “found it troubling that a case of this magnitude and that affected Mexico so significantly was not directly briefed to the Attorney General.”

Issa and other GOP lawmakers said the report does not exonerate Holder or other senior Justice Department officials for their failure to safeguard the public.

“Nothing in this report vindicates anyone,” Issa said. “If you touched, looked, could have touched, could have looked, could have asked for information that could have caused you to intervene, to complain, to worry, to talk to people and you didn’t . . . you fell short of your responsibility.”

Horowitz’s team obtained 100,000 documents, many of which Issa said were denied to the House committee, an action that led to the historic vote to hold Holder in contempt of Congress.

Among the records reviewed were 14 wiretap affidavits for Fast and Furious and another Arizona gun operation conducted in 2006 and 2007 during the George W. Bush administration. Horowitz said the applications contained “red flags” about both investigations but that none of the five deputy assistant attorneys general who reviewed them raised concerns.

Horowitz singled out one deputy, Jason Weinstein, saying that his review of the “cover memorandum” to a wiretap application, coupled with knowledge about Fast and Furious and a “heightened awareness” of similar “gun-walking” issues in Operation Wide Receiver in the spring of 2010, should have caused him to ask questions.

Weinstein, who resigned Wednesday, said the accusations against him were unfair and “demonstrably false.”

“I recognize that, in the dynamic of internal investigations of this nature, particularly when they become enmeshed in politicized Congressional hearings, it is virtually inevitable that someone must be singled out for blame, whether the facts support it or not,” he said in his resignation letter. “That is what the inspector general’s report has done with regard to me here.”

Several Republican lawmakers Thursday called for the resignation of Breuer, Weinstein’s boss.

“I can’t imagine a headline that reads, ‘Passengers charged with speeding, driver exonerated,’ ” said Rep. Trey Gowdy (R-S.C.).

The inspector general said Breuer did not authorize or know of the tactics used in Fast and Furious. But the report criticized Breuer for not informing the deputy attorney general or Holder in April 2010 when he learned that ATF had used gun-walking tactics in the Operation Wide Receiver case.

“Assistant Attorney General Breuer acknowledged last year that he should have alerted Department leadership of flawed tactics in an operation that occurred several years ago when he learned that information in 2010,” said Rebekah Carmichael, a Justice Department spokeswoman, “but the OIG report makes absolutely clear that Assistant Attorney General Breuer had no knowledge of — nor did he authorize — any investigative tactics or strategy involving Operation Fast and Furious. Nearly one year ago, Assistant Attorney General Breuer acknowledged his mistake to the Attorney General and to Congress.”

Rep. Elijah E. Cummings (D-Md.), the ranking minority member of the committee, asked Horowitz about the culpability of senior ATF officials in Washington.

Horowitz said that in March 2010, 11 months before the death in Arizona of border agent Brian Terry, ATF Deputy Director Billy Hoover was so concerned about the Fast and Furious Operation that, for the first time in his career, he asked for an “exit strategy.”

Hoover didn’t receive the strategy for six more weeks and never read it until nearly a year later.

“The fact that the deputy director could see the need for an exit strategy in March of 2010 and not receive it and review it until 2011 I think speaks volumes about what happened here in terms of failures of oversight,” Horowitz said.

Horowitz also criticized two senior Justice officials, Holder’s chief of staff, Gary G. Grindler, and his former deputy chief of staff, Monty Wilkinson, for their failure to tell Holder after Terry was shot on Dec. 14, 2010, that two firearms found at the crime scene were linked to the Fast and Furious gun-trafficking operation.

The officials “were aware of this significant and troubling information by December 17, 2010, but did not believe the information was sufficiently important to alert the Attorney General about it or to make any further inquiry,” Horowitz said.

“And so it was covered up?” asked Rep. Paul A. Gosar (R-Ariz.).

“Well, I don’t know whether it was covered up or not, but it was not told to him,” Horowitz replied.

Julie Tate contributed to this report.