WASHINGTON (AP) — The Obama administration Monday announced a plan to shift Medicare payments it makes to hospitals and doctors so they reward quality over volume. A broad cross-section of health-care industry representatives attended the announcement, including insurers, hospitals, and doctors, as well as employers, who pay for coverage for most workers and their families. Despite a slowdown in spending over the last few years, Medicare continues to grapple with longstanding financing problems, including a budget formula that will cut doctor payments by 21 percent in April unless Congress acts. Costing about $600 billion a year, Medicare is the government's flagship health insurance program, serving seniors and disabled people.