Climate change is the obvious contemporary parallel with acid rain. But if the Democrats really want to pin the denialist label on John McCain, health care is the place to focus.

The health care situation, in case you haven’t noticed, is going from bad to worse. Many smaller companies stopped offering benefits between 2000 and 2005. In the past, health coverage has tended to improve when the economy recovers from recession  but the “Bush boom” brought at best a temporary stabilization.

And now that the economy is weakening again, another plunge is in progress: last week UnitedHealth warned investors that its business is suffering because fewer employers are offering coverage to their workers.

The Democrats have been offering real plans in response; they’re not perfect, but they are serious.

The G.O.P., by contrast  and this goes as much for Mr. McCain as for the Bush administration  hasn’t even tried to address concerns about coverage. Instead, it has all been about costs, which Republicans insist (wrongly) can be dramatically reduced by a policy of, you guessed it, deregulation and tax cuts.

Until a few days ago, the only answer the McCain campaign offered to those worried about lack of coverage was the vague, implausible assertion that the magic of the marketplace would make health care cheap enough for everyone to afford.

Now Mr. McCain has admitted that maybe a government program is needed for those who can’t get private insurance. This appears to be a response to criticism from Elizabeth Edwards, who has been pointing out that deregulated insurers would deny coverage to anyone with, say, a history of cancer  a category that includes both her and Mr. McCain himself. But the way Mrs. Edwards has rattled the McCain campaign is evidence of just how vulnerable he is on the issue.