WASHINGTON — A bold federal effort to curb prescribing of painkillers may be faltering amid stiff resistance from drugmakers, industry-funded groups and, now, even other public health officials.

The Centers for Disease Control and Prevention was on track to finalize new prescribing guidelines for opioid painkillers in January. The guidelines — though not binding — would be the strongest government effort yet to reverse the rise in deadly overdoses tied to drugs such as OxyContin, Vicodin and Percocet.

But this highly unusual move — the CDC rarely advises physicians on medications, a job formally assigned to the Food and Drug Administration — thrust the agency into the middle of a long-standing fight over the use of opioids, a powerful but highly addictive class of pain medications that rang up over $9 billion in sales last year, according to IMS Health.

Critics complained that the CDC guidelines went too far and had mostly been written behind closed doors. One group threatened to sue. Then earlier this month, officials from the FDA and other health agencies at a meeting of pain experts bashed the guidelines as “shortsighted,” relying on “low-quality evidence.” They said they planned to file a formal complaint.

The CDC a week later abandoned its January target date, instead opening the guidelines to public comment for 30 days and additional changes.

Anti-addiction activists worry the delay could scuttle the guidelines entirely.

“This is a big win for the opioid lobby,” said Dr. Andrew Kolodny, co-founder of Physicians for Responsible Opioid Prescribing, a group working to reduce painkiller prescribing.

CDC Director Dr. Tom Frieden said politics did not play a role and the guidelines remain a priority.

“We want to make sure we don’t go so fast that there are questions about our process, but we certainly don’t want to see any further delay,” Frieden said. He said the FDA and other agencies support his effort, despite the negative comments from some officials.