Medicaid had nearly 73 million enrollees as of June, a number that includes low-income children and working-age Americans, for whom the program covers nearly all medical bills. It also includes several million low-income seniors and people with disabilities who use Medicaid to pay for nursing homes, prescription drug copayments and other expenses that their Medicare policies do not.

Democrats and other champions of the program generally consider Medicaid a success -- not because they think it's perfect, but because of the financial security, access to medicine and improvements in health it provides to a large group of economically vulnerable Americans. Among other things, the program's defenders note, a dramatic expansion of Medicaid through the Affordable Care Act is the primary reason America's uninsured rate has reached record lows.