The 2010 health care law has left tens of millions uninsured, leading to a groundswell of support from the left for a single-payer system, or “Medicare for All.” Health care reporter Mary Ellen McIntire explains why progressives are ready to move on, what it would take politically to get there, and how they would transform American health care.

• Single-payer health care systems are no easier in the states
• Democrats and Republicans clash over health care goals in Ways and Means

Watch: What if we switch to a single-payer health care system?