This article has been corrected. The original version (PDF) is appended to this article as a Supplement.

President Donald Trump and congressional Republicans have vowed to repeal and replace the Patient Protection and Affordable Care Act (ACA). Repealing it is relatively easy. Replacing it with “something great” is much trickier. The president has promised universal coverage and reduced deductibles and copayments, all within tight budgetary constraints. That is a tall order and unlikely to be filled by proposals that Republicans have offered thus far.

Speaker of the House Paul Ryan's blueprint (1) would rebrand the ACA's premium subsidies as “tax ...