But here’s the thing: Protecting coverage for pre-existing conditions is overwhelmingly popular, commanding majority support even among Republicans. And McCaskill has been hammering Hawley over his role in that lawsuit.

So Hawley has responded with ads claiming that he, too, wants to protect those with pre-existing conditions, as supposedly shown by his support for a bill that purports to provide such protection.

I have to say, you almost have to admire the sheer brazenness of the dishonesty here . For the bill Hawley touts is a fraud: It’s full of loopholes allowing insurers to discriminate in ways that would end up making essential health care unaffordable for those who need it most. For example, while it would require that they offer insurance to, say, cancer patients, it would allow them to sell policies that don’t cover cancer treatment — which would mean that policies that did cover such treatment would become prohibitively expensive.

And the fraudulence of this bill aside, even serious, nonfraudulent regulation of insurance companies isn’t enough in itself to provide affordable coverage for pre-existing conditions. If that’s all you do, those who sign up for coverage will be a lot sicker than those who don’t, which means a bad risk pool, which means high premiums. That was New York’s experience: Before the A.C.A., it had strong regulations on insurers, but high premiums meant that only people with health problems bought insurance on the individual market (as opposed to getting it from their employers), and this in turn kept premiums high.

To make regulation work, you have to back it up with incentives for healthy people to sign up, including subsidies that help lower-income families afford insurance. In other words, if you really want to make essential care available for pre-existing conditions while continuing to rely on private insurance companies, you need a system that looks a lot like … Obamacare. Indeed, New York premiums dropped in half when the A.C.A. went into effect.