Massachusetts' 2006 health insurance reform, hailed as a national model by top Democrats, is coming under fire from the political left. That raises doubts as to whether universal coverage supporters can overcome internal divisions. Commonwealth Care mandated that everyone in the state buy health insurance or face a tax penalty. Those who did not receive insurance via their employer could buy individual coverage through a state-managed "connector." Individuals unable to afford private insurance got subsidized coverage. Most businesses had to provide coverage or pay a penalty. Proposed reforms by both President Obama and Sen. Max Baucus, D-Mont., borrow heavily from...