Olinda Marti-Volkoff, a Medicare recipient, (center) works on a painting while taking a class with other seniors at the On Lok 30th Street Senior Center in San Francisco, Calif., on Friday, December 2, 2016. She visits the center almost every weekday for classes and to volunteer. House Speaker Paul Ryan has called for changing Medicare from the current plan, where the government pays the bills, to a defined payment plan, where seniors get a certain amount of money to buy private insurance. Studies have shown that likely means higher costs and less coverage for seniors.