The ranking Democrat on the House committee investigating the controversial federal gun-trafficking operation known as Fast and Furious accused its Republican chairman on Wednesday of stifling discussion of whether U.S. gun laws have contributed to the violence in Mexico.

A report released Wednesday by Rep. Elijah E. Cummings (D-Md.) said weak laws impede federal firearms agents trying to counter gun trafficking by Mexican drug cartels. It criticizes Rep. Darrell Issa (R-Calif.), chairman of the House Committee on Oversight and Government Reform, for making “efforts to wall off any discussion of the nation’s gun laws.”

“Chairman Issa objected to any questions about whether the nation’s gun laws could be improved to assist these law enforcement agents in their efforts to counter drug violence and firearms trafficking by Mexican drug cartels,” the report says.

In a statement, committee spokesman Frederick R. Hill responded: “This is a predictable maneuver from a minority that has sought to obstruct the investigation into Justice Department sanctioned gunwalking. It will not affect the committee’s continued focus on a reckless operation that has been linked to deaths on both sides of the border.“

Titled “Outgunned,” the 26-page report recommends stronger penalties for “straw purchasers” who illegally buy guns for others and a reporting requirement for multiple purchases of long guns, such as AK-47s. Cummings will hold a forum on the report Thursday on Capitol Hill.

On Wednesday, President Obama was asked at a news conference about Fast and Furious, the year-long investigation by the Bureau of Alcohol, Tobacco, Firearms and Explosives that allowed traffickers to move hundreds of U.S. weapons into Mexico.

“As you know, my attorney general has made clear that he certainly would not have ordered gunrunning to be able to pass through into Mexico,” Obama said. “The investigation is still pending. I’m not going to comment on a current investigation. I’ve made very clear my views that that would not be an appropriate step by ATF, and we got to find out how that happened.”

Acting ATF Director Kenneth Melson, under pressure to resign over the operation, is scheduled to testify in Congress next month.

Issa, who recently held a hearing on Fast and Furious, has called for top Justice officials to be held accountable. Issa and Sen. Charles E. Grassley (R-Iowa) have led the charge to uncover details about the operation.

Cummings’s report cites testimony from agents who criticized Fast and Furious to illustrate ATF’s lack of tools to combat gun trafficking.

“The same law enforcement agents who were invited by Chairman Issa to testify about ATF’s Operation Fast and Furious have also warned the Committee that they are incredibly outgunned in the fight against international drug cartels that are trafficking tens of thousands of military-grade assault weapons from the United States to Mexico,” Cummings said in a later statement.

Agent Peter Forcelli, a senior ATF group supervisor in the Phoenix field division, called the laws on straw purchases “toothless.” Larry Alt, a lawyer and senior ATF field agent, testified that “we don’t get traction with the U.S. attorney’s office. They don’t follow through. They don’t want to prosecute cases.”

Agents also said their efforts to combat the cartels would be strengthened with a federal statute criminalizing gun trafficking.

Issa, who returned recently from Mexico City with Cummings and other members of Congress, called Obama’s remarks “disappointing.”

“There was no sign of urgency to provide answers or explain why no one at the Justice Department has accepted responsibility for authorizing an illegal gunwalking operation six months after Border Patrol agent Brian Terry’s murder,” Issa said.

While Fast and Furious targeted Mexican gun traffickers, some of the guns involved have been linked to the killings of a U.S. Border Patrol officer and a prominent Mexican lawyer.