Washington — Efforts by Mexico and the United States to stem the skyrocketing border drug and weapons trade are failing, and both countries are to blame for the rise of violent cartels responsible for more than 6,000 deaths in Mexico last year, lawmakers and experts said in a Senate hearing Tuesday.

    For years, elected officials in Washington portrayed Mexico as being largely responsible for the problems spawned by the increasingly powerful crime syndicates -- and for fixing them.

    But at an unusual hearing of the Senate judiciary subcommittee on crime and drugs and the Senate Caucus on International Narcotics Control, lawmakers from both parties said repeatedly that Washington's inattention to decades of drug use by Americans had played a central role in the crisis.

    Many also acknowledged that their own government's failure to stop the southbound stream of weapons and laundered cash had fueled the multibillion-dollar drug trade just as much as the northbound flow of cocaine, heroin, marijuana, methamphetamine and smuggled humans.

    "Mexico and America are in this together, and there is enough blame to go around," said Sen. Richard J. Durbin (D-Ill.), the subcommittee chairman and assistant majority leader of the Senate. "The insatiable demand for illegal drugs in the United States keeps the Mexican drug cartels in business."

    He also said lax U.S. gun laws and poor enforcement had created an "iron river of guns" that had armed "Mexican drug cartels to the teeth."

    Durbin was one of several lawmakers who said Congress would begin considering ways to reduce U.S. demand for drugs through treatment and other methods.

    The Department of Homeland Security and other U.S. agencies are preparing to deploy more federal agents to the border in response to the drug cartels, one law enforcement official said on condition of anonymity because the plan was not public.

    "The number of agents has not been determined," the official said.

    Sen. Charles E. Grassley (R-Iowa), co-chairman of the narcotics caucus, said in the hearing that corruption in Mexico remained a crucial problem. But he also said U.S. authorities needed to share more intelligence and do more investigations with Mexico.

    He also said it was important to get rid of overlapping authorities between the Department of Homeland Security and the Drug Enforcement Administration.

    Sen. Dianne Feinstein (D-Calif.), the other caucus co-chair, said the U.S. government and Congress needed to do much more to help Mexico. She said the U.S. must continue to fund the security aid package known as the Merida Initiative established by the Bush administration.

    She said the promised U.S. delivery of several helicopters and surveillance equipment had been delayed until 2011, and that Washington needed to reinstitute a ban on assault weapons and give U.S. law enforcement officials greater authority to dismantle gun and drug trafficking rings.

    The hearing was the first by the Senate in this Congress to focus on the drug cartels; it followed several hearings last week in the House. It focused on how U.S. law enforcement agencies can better assist Mexican President Felipe Calderon's efforts to combat drug trafficking and related violence and corruption.

    Arizona Atty. Gen. Terry Goddard said federal agencies needed to work far better with one another, with state and local authorities, and with their Mexican counterparts.

    "We are not winning the battle," Goddard said, adding that the drug gangs easily sidestep U.S. efforts by finding new trade routes and methods of smuggling, and by using hard-to-detect methods of financing such as "stored value" debit and credit cards that can hold huge sums of money.

    "Congress can and should play a significant supporting role," Goddard said. "We can't do this alone. We need federal cooperation, coordination and resources."

    Several top U.S. officials defended their agencies' work, saying improvements were necessary but that they were cooperating better than ever with one another and with Mexico.

    William J. Hoover, assistant director of the Bureau of Alcohol, Tobacco, Firearms and Explosives, cited numerous statistics to show how many weapons traffickers and guns had been seized on both sides of the border. But he acknowledged that 90% of the guns found in Mexico came from the U.S.

    Kumar Kibble, deputy director of Immigration and Customs Enforcement, conceded that there were "a lot of intelligence gaps" in what U.S. authorities knew about how the cartels were moving their drugs, weapons and money.

    But Anthony P. Placido, the DEA's chief of intelligence, said the increase in violence was actually a sign of success. He described the cartels as "wounded, vulnerable and dangerous organizations."