Attorney General Eric Holder vigorously denied a "cover-up" by the Justice Department over "Operation Fast and Furious," telling a House panel investigating the botched gun-running program that he has nothing to hide and suggesting the probe is a "political" effort to embarrass the administration. 
 
 "There's no attempt at any kind of cover-up," Holder told lawmakers well into a hearing about whether he had been forthright in responding to requests of the House Oversight and Government Relations Committee led by Chairman Darrell Issa, R-Calif. 
 
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 "We're not going to be hiding behind any kind of privileges or anything," he said. 
 
 The hearing came after Issa and Sen. Charles Grassley, R-Iowa, his Senate partner in the probe, asserted that top Justice officials are covering up events surrounding the flawed gun-smuggling probe. 
 
 Issa made the accusation in a letter threatening to seek a contempt of Congress ruling against Holder for failing to turn over congressionally subpoenaed documents that were created after problems with Fast and Furious came to light. 
 
 Republicans also released a report in the hours ahead of the hearing claiming that Justice Department officials "had much greater knowledge of, and involvement in, Fast and Furious than it has previously acknowledged." 
 
 Asked whether his assistants, Deputy Attorney General Gary Grindler or Assistant Attorney Lanny Breuer, head of the department's Criminal Division, ever authorized gunwalking or the tactics employed in Fast and Furious, Holder responded not to his knowledge. 
 
 "Not only did I not authorize those tactics, when I found out about them I told the field and everybody in the United States Department of Justice that those tactics had to stop. That they were not acceptable and that gunwalking was to stop. That was what my reaction [was] to my finding out about the use of that technique," he added. 
 
 He added that he doesn't think that the situation warranted the kind of response Republicans were giving after his department provided thousands of documents, and planned to deliver more. 
 
 Holder also rejected arguments that his handling of the case had lost him any support for the effort he was putting forth as attorney general. 
 
 "I don't think the American people have lost trust in me. ... This has become political, I get that," he said. 
 
 But Holder also said no one has been punished "yet" in the case, despite the fact that lost guns from the operation ended up at the crime scene where U.S. Border Patrol Agent Brian Terry was murdered in December 2010. 
 
 Terry's family has informed the U.S. government that it has six months to respond to its inquiry into Terry's death or face a $25 million lawsuit. 
 
 In the botched operation, more than 1,400 weapons sold to low-level straw purchasers believed to be supplying Mexican drug gangs and other criminals were lost during tracking by Bureau of Alcohol, Tobacco, Firearms and Explosives agents. Another 700 firearms connected to suspects in the investigation have been recovered, some from crime scenes in Mexico and the U.S., including in Nogales, Ariz., where Terry was killed. 
 
 Holder said he didn't learn about Terry's murder until 24 hours after his death, and at the time did not hear that weapons tied to Fast and Furious were at the scene. 
 
 "I didn't know about Operation Fast and Furious until the beginning parts of 2011 after I received that letter from Senator Grassley, I guess at the end of January and then that was about Operation Gun Runner. I actually learned about the Fast and Furious operation in February of that year." 
 
 Holder told the committee, "I’m not sure exactly how I found out about the term, 'Fast and Furious.'" He testified repeatedly that he never authorized the controversial tactics employed in the operation. 
 
 "There is no attempt at any kind of cover-up," Holder said. "We have shared huge amounts of information" and will continue to do so, he said. 
 
 But Holder said under questioning that he has not disciplined anyone for his role in the controversial operation. 
 
 "No I have not as yet -- as yet," Holder said when questioned by Issa on the matter. "There have been personnel changes made at ATF. We obviously have a new U.S. attorney in Arizona. We have made personnel switches at ATF. People have been moved out of positions." 
 
 Holder's statements on the Justice Department's role in the operation did not sit well with Republican lawmakers on the committee, who accused the attorney general of intentionally withholding key documents in the case. 
 
 "The conclusion that I come to is there are some things in there that's being hidden that you don't want us to see," said Rep. Dan Burton, R-Ind. "We have every right under the Constitution to check on what you're doing... So for you to deny this committee anything like that is just dead wrong and I don't think you're going to find any way that you can do it." 
 
 Burton went on to say that 93,000 documents related to the operation are being withheld by the Justice Department even though they've been turned over internally to the department's inspector general, a political appointee, Burton said. 
 
 "And you're saying, well, the separation of powers prohibits you from (delivering them to Congress). That's baloney. That is just baloney," Burton said. 
 
 Rep. Jason Chaffetz, R-Utah, also questioned Holder's having not discussed the case with Secretary of State Hillary Clinton or Homeland Security Secretary Janet Napolitano. 
 
 "When people know that I'm going to be the subject of these kinds of hearings, you know six times and all that, nobody necessarily wants to get involved in these kinds of things or get dragged into it," Holder responded. 
 
 Issa told Holder the committee will do what is necessary to obtain the information, "If you do not find a legitimate basis to deny us the material we've asked for." 
 
 Holder said earlier during testimony that he would release additional materials "to the extent that I can." 
 
 In Holder's defense, Rep. Edolphus Towns, D-N.Y., claimed the committee has "not obtained one shred of evidence that would contradict your testimony." 
 
 "Not one witness, not one document, not one e-mail, and still some continue to suggest that you did personally authorize gunwalking and the tactics in Operation Fast and Furious." ||||| Washington (CNN) -- Firings and charges against the justice department officials who oversaw the agency's flawed gun-running operation are likely to come in the next six months, Attorney General Eric Holder said Thursday. 
 
 Holder was speaking before the House Oversight and Government Reform Committee to discuss the controversial sting operation called Operation Fast and Furious. 
 
 Asked what steps he had taken since the controversy came to light 13 months ago, Holder said he is awaiting the conclusions of an internal investigation. 
 
 Regarding people found culpable in that probe, he said, "I can assure you those people will be removed from federal service." 
 
 Any possible charges will not be filed until the department has the evidence to get a conviction, he said at the hearing. 
 
 The operation, designed to monitor the flow of weapons, allowed illegally purchased firearms to be taken from U.S. gun stores across the Mexican border to drug cartels. However, hundreds of weapons were lost or unaccounted for, and a storm of outrage erupted when two of the missing weapons were found at a site where Border Patrol agent Brian Terry was killed in December 2010. 
 
 Democrats and Republicans have since been at odds over who knew what about the operation and when. 
 
 At the outset of the hearing, new information on the operation was scarce, and the back-and-forth between members of the two parties dominated. 
 
 House Republican Darrell Issa threatened to begin a contempt proceeding against Holder to force him to release more documents, and pressed him for proof that such gun-running will not happen again. 
 
 Republicans are investigating how high up the operation was sanctioned, while Democrats defended Holder's testimony that he did not know about it. 
 
 The showdown comes after Issa and the Justice Department exchanged sharp letters in recent days. 
 
 The Justice Department late Wednesday sent a pointed letter to Issa rejecting his demand on Tuesday that certain documents be turned over by next week. 
 
 In his letter to Holder, Issa blasted the Justice Department for dumping -- after the close of business last Friday -- important, long-sought documents that disclosed Assistant Attorney General Lanny Breuer had discussed with Mexican officials a plan to allow illegal guns "to walk" into Mexico, where Mexican officials would arrest the gun-runners. 
 
 Issa said an e-mail showed "Breuer suggested allowing straw purchasers cross in Mexico so (Mexican authorities) can arrest, prosecute and convict." 
 
 "These new documents show that Breuer made this statement on February 4, 2011, the same day Assistant Attorney General Ronald Weich wrote to Congress denying that the department allowed guns to walk," Issa said. 
 
 The Justice Department fired back Wednesday, claiming Issa's letter showed "significant misunderstanding both of the documents we recently produced and of the Department's position on the issues you raise." 
 
 The five-page letter signed by Deputy Attorney General James Cole strongly rejected the claim that the documents show Breuer supported letting illegal guns make their way to Mexican cartels. 
 
 "Assistant Attorney General Breuer proposed to his Mexican counterparts a scenario in which those carrying illegal weapons across the border would be arrested at the border by Mexican officials and charged in Mexico. While these officials ultimately did not pursue that strategy, it is neither fair nor accurate to say that this was advocacy of 'gunwalking'. It was not." 
 
 Republicans have pressed to learn whether top Obama administration officials were aware of the controversial tactics, but to date, Breuer is the highest-ranking official shown to have any awareness of any possible gun-running operation. 
 
 Democrats have released documents suggesting the U.S. attorney's office in Phoenix and the Bureau of Alcohol, Tobacco, Firearms and Explosives field office in Phoenix were at the heart of the decision-making in developing sting operations, including Operation Fast and Furious. 
 
 Issa said in his letter to Holder that, "if the department continues to obstruct the congressional inquiry by not providing documents and information, this committee will have no alternative but to move forward with proceedings to hold you in contempt of Congress." 
 
 The Justice Department response Wednesday rejected Issa's February 9 deadline to produce all demanded documents. Cole called the deadline "impossible" to meet because of the broad scope of the request. 
 
 He did not directly refer to the threat of a contempt charge by Issa.
– Eric Holder angrily denied that the Justice Department was trying to hide anything about the botched "Operation Fast and Furious" program in his testimony before Congress today—and insisted that he'd had no knowledge of the gun-tracking operation. "There's no attempt at any kind of coverup," the attorney general said, pointing out that the department had turned over thousands of documents and intended to turn over more. "This has become political, I get that," he added, according to Fox News. "Not only did I not authorize those tactics, when I found out about them, I told the field … that those tactics had to stop," he said. (The idea was to track weapons as they made their way to cartels, but authorities lost track of many.) Holder added that those responsible would likely be fired or charged with crimes within six months, once an internal investigation is finished. "I can assure you those people will be removed from federal service," he said, according to CNN. But Republicans weren't satisfied, saying he was still withholding documents, and Darrell Issa threatened to do whatever necessary to obtain them. Issa has previously threatened to charge Holder with contempt of Congress.