A Senate panel will hear complaints on Wednesday from nursing home operators, doctors, nurses and pharmacists that a Drug Enforcement Administration narcotics crackdown has left seriously ill patients crying for pain relief.

The D.E.A. says it is merely enforcing the law that requires pharmacies to wait for prescriptions that are signed by physicians before dispensing potent painkillers like Vicodin, Percocet and morphine.

But the nursing home groups say the new enforcement rules upend many years of practice in which the government informally allowed nurses to speed the process by taking doctors’ orders orally, or from medical charts, and passing them along to pharmacies, similar to the procedures used in hospitals.

Now many of the nation’s nursing homes report delays of a day or more in getting pain drugs to patients, according to the Quality Care Coalition for Patients in Pain, a group set up by nursing home operators, pharmacists and nursing groups.