Among the many hurdles facing President Barack Obama's plan to revamp the nation's healthcare system is a shortage of primary care physicians. As Massachusetts' experience shows, extending healthcare to 50 million uninsured Americans will only further stress the system and could force many of those newly insured back into costly emergency rooms for routine care if they can't find a primary care doctor, healthcare observers told the Associated Press. To keep up with the demand for primary care doctors, the country will need to add another 40,000 to the existing 100,000 doctors over the next decade or face a soaring backlog, according to officials from the American Academy of Family Physicians.