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Attorney General Eric Holder clashed with Republicans at a House committee hearing Thursday over demands that the Justice Department turn over more documents about a flawed gun-smuggling investigation.

Chairman Darrell Issa, R-Calif., said the House Oversight and Government Reform Committee will do what is necessary to force the Justice Department to produce information on its handling of congressional inquiries on Operation Fast and Furious.

The attorney general said he will consider Issa's demand. But he said the department, with one exception, was inclined to follow a longstanding tradition of withholding internal documents about how to respond to congressional inquiries in order to preserve the ability to get candid advice from top officials.

"I think you're hiding behind something here," Rep. Dan Burton, R-Ind., told Holder. "You ought to give us the documents. ... It appears we're being stonewalled."

Issa has threatened to seek a contempt of Congress ruling against Holder for failing to provide the material. The lawmaker alleges the Justice Department is engaging in a cover-up.

"This has become political, that's fine," Holder said at the hearing, but there is no attempt "at a cover-up." The Justice Department, Holder insisted, "will continue to share huge amounts of information" about Fast and Furious itself.

The department says a Feb. 9 deadline set by Issa is too soon to process "the broad scope of the committee's requests." Some 6,000 documents have been produced, but Republicans are seeking many more.

At his daily briefing, White House press secretary Jay Carney said Holder has cooperated with Congress and "the politicization of this is pretty apparent." He said President Barack Obama thinks Holder is doing an excellent job and won't agree to calls by some GOP members for Holder's ouster.

Though neither side said so, negotiations are almost certain to be the next step.

Before the hearing started, Issa introduced Holder to federal agent John Dodson, a whistleblower in the Bureau of Alcohol, Tobacco, Firearms and Explosives who told Congress a year ago about the use of a tactic known as gun-walking in the Phoenix-based Fast and Furious investigation.

This tactic allows suspected "straw" buyers of weapons to walk away from gun stores with their purchases, rather than arresting them there. Instead, agents tried to track the low-level buyers and the guns to smuggling ringleaders and financiers, including Mexican drug cartel leaders, who have long eluded prosecution for their role in the flow of guns into Mexico. Straw buyers are those who discreetly purchase guns on behalf of someone else.

ATF's Phoenix division has tried this tactic, with minor variations, in at least four investigations beginning in 2006 during the George W. Bush administration. It began three such probes under Bush before launching Fast and Furious in the Obama administration. All of the probes encountered problems.

In Fast and Furious, agents lost track of nearly 1,400 of the more than 2,000 guns purchased by suspected straw buyers. Some 700 guns connected to suspects in the operation have been recovered in Mexico and the U.S., some at crime scenes, including the one near Nogales, Ariz., where border agent Brian Terry was murdered in December 2010.

A month after Terry's death, Congress began hearing of problems with the probe. Under pressure from lawmakers, Holder has shaken up the leadership of ATF, and the Justice Department's inspector general also is investigating the operation.

After multiple congressional hearings, including six appearances by Holder, Republicans were still voicing outrage Thursday.

Guns that walked in Fast and Furious are going to show up in Arizona "from here to whenever," said Rep. Paul Gosar, R-Ariz. "We should be sharing information."

Are "you ... capable of running the top law enforcement agency in the country?" asked Rep. Blake Farenthold, R-Texas.

In a finger-pointing response, Holder told Farenthold that critics should look at "everything I've done," including restoring the traditions of a Justice Department that had been "turned on its head" and "politicized" before Holder became attorney general in the Obama administration.

Democrats, while expressing concern about Fast and Furious, defended Holder.

"I don't see anything here today" that would warrant Holder's resignation, said Rep. Dennis Kucinich, D-Ohio. Rep. Gerald Connolly, D-Va., called the hearing "a show trial."

"This was a bottom up operation" and the attorney general did not know its details, the committee's ranking Democrat, Elijah Cummings, said after the hearing.

The dispute over Fast and Furious was exacerbated by a Feb. 4, 2011 letter to Congress in which the Justice Department said federal agents made every effort to intercept illegally purchased weapons. But in reality, agents in Fast and Furious employed the gun-walking strategy that passed up an early opportunity for arrest in the hope of making a bigger case later against ringleaders. In an exception to the policy of withholding documents about how to respond to inquiries from Congress, Holder agreed to supply memos that explain how this error was made.

A Republican staff memo created for the hearing questioned why federal agents allowed the probe to go on for over a year.

Intercepts from a Drug Enforcement Administration wiretap on one of the straw buyer suspects provided probable cause for federal agents to make arrests, or at the very least supplied the basis to seize the weapons, the Republican staff memo said. The memo said ATF did not act on this information.

Democrats on the committee pointed out that agents in the case testified that stronger U.S. laws are needed against straw buyers, because cases get thrown out of court, or prison sentences are too short to persuade the low-level buyers to turn on their bosses.