Washington (CNN) -- Attorney General Eric Holder withstood a four-hour grilling Thursday dominated by Republican House members seeking to lay blame on Holder for a botched gun-smuggling sting operation.
But in his seventh congressional hearing on the Bureau of Alcohol, Tobacco, Firearms and Explosives' Operation Fast and Furious, Holder left largely unscathed after standing by previous claims he knew nothing about the flawed tactics until early last year.
The high-stakes, election-year face-off comes amid repeated GOP threats the House may find Holder in contempt for failing to respond to subpoenas for Justice documents on the operation.
Rep. Darrell Issa, R-California, led the attack two days after he disclosed secret court documents he obtained from "whistle-blowers." Issa said the applications for wiretaps he was given show top Justice officials were aware early on that illegally purchased weapons in Arizona had ended up in the hands of Mexican cartels.
Issa, who is chairman of the Oversight Committee investigation of Fast and Furious, blasted Holder for not turning over additional documents he has demanded.
"Nothing has come from your department, not a shred of paper," Issa said. He dismissed the more than 7,000 pages of Justice documents received earlier this year.
Issa demanded to know if Holder and his aides had begun to pull together the documents the committee wants. Holder declined to answer.
Holder then said the documents don't back Issa's claims of high-level knowledge of the operation.
"There's nothing in those affadavits as I've reviewed them that indicates that gun-walking was allowed," Holder said. "I didn't see anything in there that would put on notice a person who was reviewing them ... knowledge of the fact that these inappropriate tactics were being used," he added.
The Justice Department, which oversees the Bureau of Alcohol, Tobacco, Firearms and Explosives, has acknowledged that the plan, which allowed illegally purchased guns to "walk" across the border into Mexico, was badly flawed. Such sting operations have now been prohibited. The ATF, which lost track of more than a thousand firearms after they crossed the border, found itself under fire when two of the lost weapons turned up at the scene of the killing of U.S. Border Patrol Agent Brian Terry in December 2010.
Terry's family has been among critics of the Holder Justice Department's handling of the case.
Holder appears before the Democratic-controlled Senate Judiciary Committee next week, where Fast and Furious is likely to again be a major topic.
On Thursday, members of three congressional caucuses said in a letter to House Speaker John Boehner, R-Ohio, that threats to hold Holder in contempt of Congress are unwarranted. Leaders of the Black Caucus, Hispanic Caucus and Asian Pacific American Caucus wrote that the Justice Department has gone to "great lengths" to answer the committee's questions and said, "We are concerned that threats of contempt proceedings would distract the Nation's chief law enforcement officer from vigorously enforcing the nation's laws."