WASHINGTON — Obama administration officials, alarmed at doctor shortages, are looking for ways to increase the supply of physicians to meet the needs of an aging population and millions of uninsured people who would gain coverage under legislation championed by the president... Senator Max Baucus, a Montana Democrat and chairman of the Finance Committee, said Medicare payments were skewed against primary care doctors — the very ones needed to coordinate the care of older people with chronic conditions like congestive heart failure, diabetes and Alzheimer’s disease... “Primary care physicians are grossly underpaid compared with many specialists,” said Mr. Baucus, who...