Washington • More than 30 U.S. senators demanded information Friday on the 2016 law that stripped the Drug Enforcement Administration of its most potent weapon against companies suspected of spilling hundreds of millions of addictive painkillers onto the black market.

Thirty-one Democrats and two independents noted that the same law required the DEA and the Department of Health and Human Services to compile a report for Congress on the law's impact by April 16. Six months later, no report has been submitted.

They demanded an immediate update, saying they "want to ensure the Drug Enforcement Administration (DEA) and other related agencies have all of the tools necessary to fight this epidemic."

In a joint investigation, The Washington Post and "60 Minutes" reported Sunday that a small number of members of Congress, allied with parts of the drug industry, had pushed through a law that undermined DEA efforts against wholesale drug distributors that have allowed pain pills to get into the hands of users and dealers.

In the House, that effort was led by Rep. Tom Marino, R-Pa., who overcame years of opposition from the DEA to win passage of a version of the law that would have hamstrung the agency even more severely. The legislation was slightly altered during negotiations with Sen. Orrin Hatch, R-Utah, before it cleared the Senate and was signed last year by President Barack Obama.

Marino was President Donald Trump's nominee to become the nation's drug czar. He withdrew his name Tuesday in the wake of the reports. In a statement on his website, he blasted the reports and accused a former DEA official, Joseph Rannazzisi, of trying to deflect blame for a failure to stem the U.S. opioid crisis. For 10 years, Rannazzisi led the DEA's crackdown on wholesale opioid distributors.

Hatch said on the floor of the Senate and wrote in an op-ed in The Washington Post that he worked with the DEA and the Justice Department to craft the final language. Either department or any senator could have stopped the bill, he said. But The Post and "60 Minutes" reported that DEA officials accepted the language only after concluding it was the best deal they could get.

In Friday's letter, the senators wrote that "as members of Congress from states severely affected by the nation's addiction epidemic, we are concerned by these recent news reports and the issues they raise, and we write to request that you immediately provide Congress with an update on the law's impact on the war against addiction." The letter was addressed to acting HHS secretary Eric Hargan and acting DEA administrator Robert Patterson.

The effort was led by Sens. Sherrod Brown, D-Ohio, Richard Durbin, D-Ill., and Edward Markey, D-Mass., who represent three states where the opioid epidemic is severe. About 200,000 people have died of overdoses of prescription opioids since 2000, and tens of thousands more have succumbed to heroin and fentanyl.

Sen. Charles Grassley, R-Iowa, has promised an oversight hearing soon on the law, titled the Ensuring Patient Access and Effective Drug Enforcement Act of 2016. Deputy Attorney General Rod Rosenstein also promised a review of whether the law hurts DEA enforcement efforts.

Numerous lawmakers, most of them Democrats, have called for repeal or amendment of the law.