The proposal aims to reduce government spending on health care for the young and middle-aged. Much of what it does allow would pay for tax credits to help people buy health insurance. Everyone — lower-, middle- and upper-class — of a certain age group would get the same amount of help, even if some wouldn’t need it to pay premiums and others would struggle to make premium payments of any kind without assistance. . . .

Those with preexisting conditions would find some protection in Mr. Gillespie’s program but with strict limits. If they went without health insurance for even relatively brief amounts of time, for example, insurance companies would be able to hike their rates or refuse them coverage, locking them out of the ordinary insurance market. In addition, the repeal of Obamacare’s consumer protections would allow insurance companies to deter high-risk patients by carefully shaping their coverage plans — refusing to cover certain HIV or cancer medications, for example.