Imagine a man who for some reason is determined to stuff a balloon into a box — a box that, aside from being the wrong shape, just isn’t big enough. He starts working at one corner, pushing the balloon into position. But then he realizes that the air he’s squeezed out at one end has caused the balloon to expand elsewhere. So he tries at the opposite corner, but this undoes his original work.

If he’s stupid or obsessive enough, he can spend a long time at this exercise, trying it from various different angles, and maybe even briefly convince himself that he’s making progress. But he’s kidding himself: No matter what he does, the balloon isn’t going to fit in that box.

Now you understand what’s happening to G.O.P. efforts to repeal and replace the Affordable Care Act.

Republicans have spent many years denouncing Obamacare as a terrible, horrible, no good law and insisting that they can do much better. They successfully convinced many voters that they could preserve the good stuff — the dramatic expansion of coverage that has brought the percentage of Americans without health insurance to a record low — while reducing premiums, shrinking deductibles and, of course, doing away with the taxes on high incomes that pay for the program.