(Bloomberg View) — Trying to repeal Obamacare has long been a popular (if futile) Republican pastime. Now replacing Obamacare is catching on, at least among Republican presidential candidates. This would count as progress, except that none of their proposals quite meets the definition of "replacement." 

The whole point of health care reform is, or should be, relatively straightforward: providing the best possible health insurance to the largest possible number of people at the lowest possible cost. How do the candidates' various proposals fare under these criteria? 

Under Wisconsin Governor Scott Walker's plan, released Tuesday, 6 million more people reportedly would have private health insurance than under Obamacare. How many would lose government-sponsored coverage, however, is left for voters to guess. Senator Marco Rubio's outline, also unveiled last week, doesn't mention the effect on insurance levels at all. But it's unclear how any plan that rolls back the expansion of Medicaid, as both plans do, could insure as many people as Obamacare does through other means.