WSJ has a copy of the report: "Agents Resisted Weapons Tracking."

Evan Perez writes:

Federal agents battled their supervisors to stop a government program that kept illicit guns in circulation to trace them to weapons traffickers, a new congressional report shows.

Some agents even worried that a gun tracked, then lost, in the program might have been used in the January shooting of Rep. Gabrielle Giffords. That didn't turn out to be the case, but other guns tracked by the Bureau of Alcohol, Tobacco, Firearms and Explosives did end up at other crime scenes in the U.S. and Mexico.

The Phoenix ATF office devised the operation known as Fast and Furious in 2009-10 to monitor weapons purchases by suspected gun traffickers. The agency hoped to build a case against major arms smugglers to Mexican drug cartels.

Some lawmakers say the ATF didn't have the means to track the guns and should have known that such tactics would backfire. The report says the ATF work resulted in a case against small-time smugglers, not major traffickers.

ATF agents interviewed by congressional investigators described supervisors trying to tamp down agents' misgivings about the strategy to allow the weapons purchases.

Larry Alt, an ATF agent, told investigators agents opposed the weapons sales as early as December 2009 and wanted to arrest straw purchasers, who are paid to buy guns for others. Mr. Alt said he agreed with a fellow agent who expressed the view that "someone was going to die."

Supervisors responded by saying the operation was "sanctioned" by higher-ups. They also cited Mexico's surging drug violence—187 murders in Sinaloa state in one month— as reason for the strategy.

"I believe we are righteous in our plan to dismantle this entire [trafficking] organization and to rush in to arrest any one person without taking into account the entire scope of the conspiracy would be ill advised. ...," wrote David Voth, an ATF supervisor who was leading Fast and Furious, to fellow agents in an April 2010 email cited in the 51-page report scheduled to be released Wednesday.

Congressional scrutiny grew over the ATF operation after the shooting last December of a U.S. border agent, Brian Terry. At the crime scene, investigators found two assault rifles purchased from a gun store that the ATF was monitoring as part of Fast and Furious.

Rep. Darrell Issa, chairman of the House Oversight and Government Reform Committee, and Sen. Chuck Grassley, top Republican on the Senate Judiciary Committee, are leading a probe of the ATF operation. Mr. Issa is scheduled to hold a hearing Wednesday with ATF agents who raised objections about the tactics and family members of Mr. Terry.

The lawmakers have raised questions about whether top officials at the Justice Department, which oversees the ATF, were involved in approving the Phoenix operation. The congressional report cites testimony from agents saying supervisors pointed to approval from the federal prosecutors in the Phoenix U.S. attorney's office and ATF headquarters.

Tracy Schmaler, Justice Department spokeswoman, said the department issued guidance to law enforcement agencies "that under no circumstances should guns be allowed to cross the border into Mexico." She said Attorney General Eric Holder has asked the department's inspector general to investigate.

Ricardo Alday, spokesman for the Mexican Embassy in Washington, said the Mexican government "will be awaiting the results of the investigation" but would withhold further comment.

Lawmakers allege that more than 2,500 firearms were purchased by suspected traffickers during the operation.

After the Terry killing, Phoenix prosecutors filed charges against 20 alleged weapons smugglers, who they said trafficked about 400 firearms to cartel gangs. Prosecutors separately have charged one man arrested at the scene in the Terry killing. Neither the assailant not the weapon in the agent's killing have been identified.

The congressional report details testimony from Mr. Alt, an 11-year ATF veteran; Olindo Casa, an 18-year veteran; Pete Forcelli, who was a New York City police detective before joining the ATF in 2001, and John Dodson, who contacted lawmakers after he said he was removed from the Fast and Furious operation because of his dissent.

The tactic of letting the weapons purchases continue despite evidence that some of the firearms were turning up at crime scenes in Mexico was new to veteran agents, according to the congressional report. Agents even stood behind the counter at gun stores to watch purchases but were told they couldn't intervene, the report said.

Mr. Forcelli described a screaming match between agents and supervisors over police radio about the orders to let the purchases continue.

Gun-store owners were told to cooperate with the probe, the report says. Mr. Dodson told investigators that gun-store owners were told to proceed with sales even when "a 22-year-old girl walks in and dumps $10,000 on… AK-47s in a day, when she is driving a beat up car that doesn't have enough metal to hold hubcaps on it."

Tensions in the Phoenix operation were well-known, according to the congressional report.

Mr. Voth wrote about the disagreement in an email, cited in the report: "It has been brought to my attention that there may be a schism developing amongst the group…"

"We are all entitled to our respective (albeit different) opinions however we all need to get along and realize that we have a mission to accomplish."

He added: "Whether you care or not people of rank and authority at HQ are paying close attention to this case and they also believe we are doing what they envisioned."