The House was to vote Thursday on the bill, which cleared the Senate by an overwhelming margin in March.
The bill would allow people with certain serious or debilitating conditions that could be alleviated by marijuana to possess up to six ounces of the drug if they obtain a doctor's written recommendation.
Senators approved the bill after lowering the proposed minimum age for qualifying patients from 21 to 18.
But an amendment introduced Wednesday by Republican Rep. Don Blakey of Dover removes the age limitation and would make medical marijuana available to all patients that might benefit, regardless of age.
