The chairman of the House oversight committee, Rep. Darrell Issa, R-Calif., said Sunday that he could issue subpoenas to the Obama administration as soon as this week over the botched Fast and Furious gun-walking operation.

Issa suggested on Fox News Sunday that Attorney General Eric Holder knew about Fast and Furious earlier that he admitted to in his congressional testimony, The Associated Press reported.

Why are they denying knowing about something that they were briefed on? Issa said. Exactly when, the American people want to know, how did it happen?

The 2009 Fast and Furious operation was designed to bring down Mexican cartels importing U.S.-bought weapons and shipping drugs to the United States. In the operation, Bureau of Alcohol, Tobacco, Firearms and Explosives (ATF) agents allegedly allowed thousands of weapons to cross the border and fall into Mexican drug cartel hands, CBS News reported.

It's called letting guns walk, and it remained unknown to the public until Border Patrol Agent Brian Terry was murdered last December; two Fast and Furious guns were found at the scene and ATF agent John Dodson blew the whistle. It was also learned that the ATF agents lost track of more than 1,000 firearms during the operation last year.

On May 3, the attorney general claimed in congressional testimony that he had only recently learned about the gun-walking program his Justice Department was running with the ATF.

I'm not sure of the exact date, but I probably heard about Fast and Furious for the first time over the last few weeks, Holder testified.

Yet new documents directly contradict Holder's statement to Congress, leaving House Republicans asking for a special probe. Sen. Chuck Grassley, R-Iowa, and Issa, released a series of heavily redacted memos apparently sent to Holder from Michael Walther, the director of the National Drug Intelligence Center. In them, an operation is described as involving the straw purchase of hundreds of firearms that went to Mexican drug cartels.

In a letter sent Friday to key lawmakers who oversee Justice Department issues, Holder said his testimony was truthful and accurate and said Republicans are engaging in a political game of gotcha.

Such irresponsible and inflammatory rhetoric must be repudiated in the strongest possible terms, Holder said.

On Fox, Issa said President Barack Obama still seems to have full confidence in Eric Holder - something I don't share.

Refusing to join other Republicans who are calling for the appointment of a special prosecutor to investigate Holder, Issa said: Congress is well along the way of investigating this operation to find out what went wrong, who knew it and what we have to do in the future to make sure it can't happen again.

House Judiciary Committee Chairman Lamar Smith, R-Texas, was sending a letter to Obama on Tuesday, asking the president to instruct the Department of Justice to appoint a special counsel, saying Holder cannot investigate himself.

At Issue: Did Attorney General Make A False Statement Under Oath?

The investigation seeks to ferret out whether Holder purposefully made the false statements while under oath. One document, dated July 2010, shows Walther, director of the National Drug Intelligence Center, told Holder that straw buyers in the Fast and Furious operation are responsible for the purchase of 1,500 firearms that were then supplied to the Mexican drug trafficking cartels.

Other memos show that Holder started receiving weekly briefings on the Fast and Furious program from the National Drug Intelligence Center beginning, at the latest, on July 5, 2010, Smith wrote.

The updates mentioned, not only the name of the operation, but also specific details about guns being trafficked to Mexico, Smith wrote in his letter to the president. Allegations that senior Justice Department officials may have intentionally misled members of Congress are extremely troubling and must be addressed by an independent and objective special counsel. I urge you to appoint a special counsel who will investigate these allegations as soon as possible.

The Department of Justice, however, defended Holder in a statement Tuesday, saying:

The Attorney General's testimony to both the House and the Senate was consistent and truthful, it read. He said in both March and May of this year that he became aware of the questionable tactics employed in the Fast and Furious Operation in early 2011 when ATF agents first raised them publicly, and at the time, he asked the Inspector General's office to investigate the matter.

The House Judiciary Committee's request for a special counsel is the third such request in the last two years. In October 2009, Smith asked for a special counsel to investigate ACORN, a community organizing group. In July 2010, Smith requested an investigation into the New Black Panther Party on charges of voter intimidation.

Following the release of the memos, a Justice Department official said that Holder has consistently said he became aware of the questionable tactics in early 2011 when ATF agents first raised them publicly, and then promptly asked the (inspector general) to investigate the matter.

According to the official, Holder testified in March 2011, to a Senate Appropriations subcommittee, of that development; the Justice Department official also said Holder regularly receives hundreds of pages, none of which contained information regarding the Fast and Furious operation or its potential problems.

The weekly reports (100 + pages) are provided to the office of the AG and (deputy attorney general) each week from approximately 24 offices and components. These are routine reports that provide general overviews and status updates on issues, policies, cases and investigations from offices and components across the country. None of these reports referenced the controversial tactics of that allowed guns to cross the border, the official said.

(House Oversight and Government Reform Committee Chairman Darrell) Issa of all people, should be familiar with the difference between knowing about an investigation and being aware of questionable tactics employed in that investigation since documents provided to his committee show he was given a briefing that included the fast and furious operation in 2010 -- a year before the controversy emerged, the official continued.

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