It's the same story in the West Virginia Senate race: A Democratic incumbent, Joe Manchin, is up against a Republican attorney general, Patrick Morrisey, who joined the lawsuit. Manchin is hitting Morrisey hard over the issue.

Some Senate Republicans are trying to contain the political fallout from the lawsuit by introducing legislation they vow to enact if it succeeds. That legislation purports to prohibit insurers from discriminating against people with pre-existing conditions, but it is poorly drafted. Its text requires insurers to cover people without regard to their health status, but does not appear to require the insurers to cover the conditions for which the patients need treatment.

Republicans are on stronger ground defending their previous legislative record, or would be if more of them were conversant with the issues. There, the key item of contention is a part of the House Republican bill that would have let states apply for waivers from Obamacare's regulations. In states with waivers, insurers would have been allowed to charge higher premiums to people who went without insurance, got sick and then tried to sign up.

In theory, that system would keep premiums lower by deterring people from gaming the system. Healthy people would have an incentive to buy insurance rather than wait until they got sick.

The bill would not have taken people with chronic health conditions back to the situation they were in before Obamacare. Even in waiver states, they would have Obamacare's regulatory protections so long as they maintained continuous coverage. And it would be easier to maintain continuous coverage than it had been before Obamacare. The bill largely maintained Obamacare's subsidies for people without access to employer coverage, Medicare or Medicaid.

Those with chronic conditions but no coverage, meanwhile, would have access to government-financed high-risk pools. These pools were, admittedly, oversubscribed before Obamacare. But the subsidies for people in the individual market and the regulatory protection for those who maintained coverage would both work to shrink the applicant pool.

It should also be remembered that, especially in the post-Obamacare landscape, state officials would have a powerful political incentive not to jeopardize affordable coverage for people with pre-existing conditions. The current campaign is itself evidence that the goal of keeping them covered has strong political support.

None of this puts the Republican legislation beyond critique. The Congressional Budget Office, which has long reflected the assumptions of liberal policy experts on health issues, asserted that the waivers could cause serious harm to insurance markets. Its projection, however, partly reflected its confidence that ending Obamacare's fines on people without insurance — another feature of the Republican bill — would have large destabilizing effects. The CBO has backed away from that view; and anyway, the fines have subsequently been ended in different legislation.

But there is certainly a policy debate to be had on these issues. It's too bad for the Republican candidates this year that so few of them have shown any ability to engage in it.

Ramesh Ponnuru is a Bloomberg Opinion columnist. He is a senior editor at National Review, visiting fellow at the American Enterprise Institute and contributor to CBS News. This column does not necessarily reflect the opinion of the editorial board or Bloomberg LP and its owners.

Read more about what's in store for the ACA this election season:

• What the Texas Obamacare lawsuit means for midterms
• States attacking ACA's pre-existing condition protections have the most to lose
• GOP abandonment of ACA a gift for Democrats?

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