On and after January 1, 1991, the Commissioner of Social Services may provide, in accordance with federal law and regulations and within available appropriations, medical assistance under the Medicaid program to (1) children over five and under nine years of age whose families have an income below one hundred per cent of the federal poverty level and (2) elderly and disabled persons who would be eligible to receive supplemental security income benefits except for income and who have incomes below one hundred per cent of the federal poverty level.