ALBANY — When Gov. Andrew M. Cuomo announced this month that he would allow medical marijuana in New York, the news was greeted with great enthusiasm by those who champion the drug for patients with cancer, AIDS and other serious illnesses.

But the initial euphoria has abated, as those same supporters have questioned Mr. Cuomo’s plan, with few answers so far.

The administration has yet to detail the 20 hospitals statewide where medical marijuana would be available, in what forms it would be dispensed, or — perhaps most critically — where the state would get its supply. Nor has the governor made clear what the plan would cost, or who would pay for it.

And while advocates say they appreciate the governor’s support, they are using the uncertainty about his proposal, which hinges on an obscure, never-implemented 1980 law, to push for new legislation that would include specifics, like how patients, physicians, and producers of marijuana would be chosen.