PRESIDENT OBAMA’S health-care reform celebrated its birthday last weekbut not very happily. Republicans, who gained control of the House last fall in part by attacking the reform, redoubled their threats to strangle the 1-year-old in its crib. Democrats defended the bill but, well, defensively.

The reform is far from perfect, but Republicans are more wrong than right in their attacks. Their vitriol on the subject will make difficult or impossible the improvements the system is sure to need. But the politics of health reform are even more muddled and difficult than the reform itself, so it’s not surprising that their irresponsible opposition gains traction.

There is a disconnect between the goals of reform and what voters want. For most Democrats, the primary objective was to guarantee health insurance for all Americans. Presumably this goal is popular among the 15 percent of the population without insurance, and other Americans would be happy not to have to worry about losing theirs.

But many in the first group don’t vote, and many in the second don’t like the idea of having to help pay for health care for those without. So Congress and the president worked hard to disguise or postpone the true cost of this new entitlement.

The second objective — and, in our view, the most important for the nation’s well-being — was to control the rise in health-care costs. These have been swallowing state (because of Medicaid) and federal (Medicare, veterans and military) budgets. If trends aren’t reversed, government will pretty soon be spending most of its money on health care and on interest on the growing debt.

In theory, spending less could go hand in hand with being healthier. Investments in prevention could reduce the incidence of costly, chronic illness, which would be good for people as well as pocketbooks. Reducing medical errors and hospital infections would have a similarly dual effect. But controlling costs will also require rigorous study of which drugs and procedures work and which don’t — with government and insurance companies refusing to pay for things that don’t justify the cost. This will make plenty of doctors, drug and device companies, and patients unhappy — witness the recent flare-up over mammograms — and will be easily spun into specters of “rationing” and “death panels.”

Given the political liabilities associated with these two main goals, the administration has emphasized a third objective, that of making insurance companies more consumer-friendly: allowing young adults to stay longer on their parents’ policies, requiring coverage for people with prior conditions and so on. Even this is tricky, though, because all these items make health insurance more costly. Someone has to pay.

We supported the reform because we believed in the first goal — that no one should go without health care — and because the reform contained significant seedlings of cost control. But nurturing those was always going to be challenging, and with Republicans more interested in scoring points than making the system work better, many of them may get stomped on.

Republicans for the most part don’t offer alternative ideas to extend coverage to the uninsured. They do claim to be concerned about costs, and some of them espouse ideas that Mr. Obama would have been wise to embrace — tort reform, for example, and, more important, ending the tax exemption for employer-provided insurance, which distorts incentives and encourages overspending. But their root solution — competition and the free market — won’t go far enough. It may make sense for optional treatments, such as cosmetic or Lasik surgery, but it can’t encourage preventive services that pay off years later, and the seriously ill are frequently not in a position to do comparative shopping.

So at best the country is going to have to come back to this reform again and again, improving and reshaping as more is learned about how to control costs. Once it goes into force, after 2014, there will be unanticipated effects. Many more employers than predicted may stop offering insurance and dump their workers on the public exchanges, which could destabilize a system the administration has vowed not to upend. The relatively small penalty on the uninsured may not be enough to induce healthy young people to buy insurance, which could lead to higher rates for everyone else. The effort to reimburse hospitals and doctors for keeping patients well, rather than paying them procedure by procedure, may encourage shortcuts in care.

You can imagine tweaks and fixes for all of these. That’s true, too, if the Supreme Court finds unconstitutional the mandate to buy health insurance; Congress could impose a tax instead of a penalty or create other disincentives to the uninsured — barring them from buying subsidized insurance when they do get sick, for example.

But Republicans set on strangling Obamacare won’t look kindly on tweaks or fixes; they will take any setback as proof of failure and do everything they can to keep the system from working. If they had a viable alternative, that would be a less frightening prospect.