On Wednesday, The Hill ran this very interesting story on the prospects for health care reform if either Senator Hillary Clinton or Senator Barack Obama were to win the presidential election in November.

Both Democratic candidates, of course, have spent months telling voters they are just the leaders the country needs to swiftly pass a major health care overhaul. Both have offered somewhat sketchy proposals that nonetheless promise the moon to voters — new subsidies to buy insurance, a publicly-run insurance option, and a federally-administered “exchange” where people can get private insurance.

But, now, it seems some in Congress are beginning to realize — perhaps after reading the candidates’ plans — that it won’t be so easy to pass them.

They’re right. The Democratic proposals, as described to voters so far, could never pass because they will not stand up to the kind of analytic scrutiny needed for realistic legislation. They would completely disrupt employer-based insurance pools, which would mean forcing millions of people to switch out of coverage they generally like today. And neither Democratic candidate has described anything resembling a plausible cost-control strategy. Consequently, their new subsidy promises will be “scored” as escalating at well above the rate of economic growth, which means ever higher tax rates or deficits.

Senators Jay Rockefeller and Charles Schumer are quoted in the story, and they clearly want to throw some cold water on the over-heated expectations of Democratic activists. But it might be too late for that. The Democratic presidential candidates themselves have raised expectations, and they are unlikely to say anything before November to take air out of the health care balloon. That will have to wait until late this year or early next year (if they are elected), at which point they will run the risk of alienating many voters who took them at their word.