Nobody said reforming Medicare was going to be easy, and the backlash to the Obama administration's proposed changes about the way doctors are paid by the massive entitlement program shows why.

Loud critics, such as doctors and patient advocacy groups, have emerged in response to the administration's attempted reform of Medicare Part B, the part that covers outpatient services, including treatment for serious conditions at specialty clinics.

Oncologists and others who administer expensive drugs to patients through Medicare are worried that a new payment model the administration has floated will cut into their margins or even make their practices financially nonviable.