Sen. Bernie Sanders is drawing unprecedented support from Democrats for his proposal to implement a government-run healthcare system in the U.S., but the bill doesn’t address several questions that are likely to emerge as some lawmakers advocate on behalf the legislation.

Under the Sanders healthcare plan, called the Medicare for All Act, Medicare would pay for emergency surgery, prescription drugs, mental healthcare and eye care without a co-pay. Soon after it would be passed into law, people 18 and under would receive a “universal Medicare card” and others currently not eligible for Medicare, even those who now have private plans, would be phased into the program after four years.