Former acting Drug Enforcement Administration head Chuck Rosenberg has declined to discuss his role in the drafting of the bill. (Alex Brandon/AP)

A Los Angeles congresswoman who co-sponsored a controversial law that has hobbled the Drug Enforcement Administration said Tuesday that the head of the agency personally assured her that the measure would not hamstring law enforcement efforts.

Rep. Judy Chu (D-Calif.), an original co-sponsor of the bill, called Tuesday for an investigation into whether the law is harming enforcement against "bad actors" and requested hearings to examine whether she was misled.

Chu, in a letter to the chairmen of two key House committees, said then-acting DEA administrator Chuck Rosenberg told her in a Sept. 22, 2016, meeting after the measure became law that it "did not interfere with the DEA's ability to successfully stop bad actors."

Her letter is the first to detail Rosenberg's position on the law since The Washington Post and "60 Minutes" revealed Sunday that it stripped the DEA of its most potent weapon against drug distributors that have allowed hundreds of millions of narcotic painkillers to spill into the black market.

The law, the Ensuring Patient Access and Effective Drug Enforcement Act, was primarily pushed by Rep. Tom Marino (R-Pa.) — who withdrew Tuesday from consideration to be the nation's next drug czar after the reports sparked angry reaction to his role.

Chu said in her letter that she had been concerned after reading a July 10, 2016, Los Angeles Times account of dissent within the DEA over the law, which had been signed by President Barack Obama three months earlier, and that she had asked for a meeting with Rosenberg.

During the meeting, Chu wrote, "I learned that the DEA had provided consultation during the drafting of H.R. 471, and while the agency felt the legislation was unnecessary, he reiterated that it was not the agency's position that this bill would interfere with the agency efforts to stop harmful opioids from entering our communities."

The Post and "60 Minutes" reported Sunday that DEA and Justice Department representatives signed off on the final wording of the Senate bill that became law after lengthy negotiations with the staff of Sen. Orrin G. Hatch (R-Utah). Hatch made that point in a speech on the Senate floor Monday.

But DEA officials said the agency was forced to accept a compromise it did not want to avoid language that would have crippled enforcement even more. Emails cited in the story supported that position.

"They would have passed this with us or without us," said one DEA official, who spoke on the condition of anonymity. "Our point was that this law was completely unnecessary."

The DEA's chief administrative law judge, John J. Mulrooney II, has concluded that the law makes it all but impossible for the agency to freeze the shipments of large drug distributors via an "immediate suspension order."

"If it had been the intent of Congress to completely eliminate the DEA's ability to ever impose an immediate suspension on distributors or manufacturers, it would be difficult to conceive of a more effective vehicle for achieving that goal," Mulrooney wrote in an article to be published in the Marquette Law Review.

The DEA did not respond to requests for comment Tuesday, and Rosenberg has declined to comment.

Chu, one of the few Democrats to co-sponsor Marino's bill, said in her letter to the committee heads that she "believed it would help independent and community pharmacists, most of whom are small business owners who provide vital services for their communities."

She asked the House Energy and Commerce committee and the Oversight and Government Reform Committee to look into the matter.