I t’s five years after passage, and the landmark reforms championed by a progressive president have survived two election campaigns in which opponents have called for their repeal. The leading critics in the business sector seem resigned to working with the new law. And the major implementation milestones have been met, though the slow rollout means that tangible benefits have only just become apparent. Yet all this is not enough to ensure that the law will achieve its key purposes. Without additional reforms, the act passed with much fanfare five years prior will not guarantee universal coverage. More important, it will remain inadequate in key areas, with the real, continuing danger that its limited funding will be outrun by skyrocketing costs.

It sounds like a forecast of where the Affordable Care Act (ACA), the landmark health-care legislation passed earlier this year, will be in 2015. But in fact it describes the actual historical standing of the Social Security Act on the law’s fifth anniversary in 1940. During the 1936 presidential campaign, Republican candidate Alf Landon had criticized the legislation as a “cruel hoax”–and gone down to defeat. By the end of 1937, the Supreme Court had affirmed the act’s constitutionality, and its “old-age insurance” component, which we now call Social Security, had been implemented successfully (although states were dragging their heels on other parts of the legislation, such as public assistance for the poor). But Social Security covered only half the population. Worse, its benefits were meager and not tied to inflation. As prices rose, those benefits were destined to fall, and they did. It would be another ten years before the program was put on a stronger foundation with the Social Security Amendments of 1950, the founding law for the modern program.

This last chapter in Social Security’s early history may seem to promise a happy fate for health-care reform–if not in the next decade, then beyond. Indeed, many advocates of the law have declared that a similar expansionary process will play out today. Here’s Paul Krugman: “Highly imperfect insurance reforms, like Social Security and Medicare in their initial incarnations, have gotten more comprehensive over time. This suggests that the priority is to get something passed.”

It’s true that, even by 1940, the Social Security Act had already been expanded. Amendments passed in 1939 created survivors’ benefits and moved up the first payment of benefits to 1940 from the original 1942. But that expansion had been supported by conservatives who wanted to rein in the program: In return for the larger, earlier benefits, the amendments eliminated the program’s reserve fund, making it fiscally vulnerable. Without the reserve fund and with conservatives blocking the payroll-tax increases needed to fund adequate benefits, the program languished over the next ten years. And Social Security was a simple, understandable program, enacted in a far more favorable political climate than greets the intricate and far-less-understandable ACA. If Social Security faced hard sledding, the cause for vigilance and determination with regard to the ACA is all the greater.

The story of the Social Security Act offers a salient reminder to today’s health reformers: Implementation of a law is only part of the challenge of social reform. The other, more daunting part is building support for the improvement and expansion of the inevitably jerry-rigged programs that can pass through America’s polarized and fragmented legislative process. Democratic Senator Tom Harkin of Iowa rightly calls the health-care law a “starter home,” with the need for plenty of renovation. Unfortunately, the home is not built yet, and the construction zone is in the path of a hurricane: the perfect storm of runaway costs and unbridled conservative attacks on the law.

In 2015, the full force of this storm will not yet have hit. The Obama Administration will have been through a series of battles over how to implement and enforce the law, and while not all the tests will have been met, the basic building blocks of the law will almost certainly be in place. Millions of Americans who are uninsured today will have coverage, and those who already have coverage will have much greater assurances that they can obtain it even if they lose or change jobs, become sick or disabled, or live in a family with someone who experiences such events. The result will be increased public support for the law, albeit in a climate of continuing suspicion and acrimony in which conservative opposition remains strong and misinformation rife.

And yet these partial successes will also showcase the gap between the rhetoric of reformers and the reality of reform. While millions will be newly insured, millions more will still lack basic protections: They will fall through the law’s cracks, or they will be exempted from its requirement to buy coverage because they cannot afford the premium. Medical costs will still represent a painful hit to family incomes. And families who don’t qualify for generous subsidies will still find insurance shockingly expensive.

In short, reformers will discover the same painful truth made vivid by Social Security’s stagnation after 1940: Maintaining the legislative status quo against the forces crying “repeal and replace” is not enough. The reforms launched with the ACA will need to be pushed forward or they will fall increasingly short. Every crucial aspect of the act–the reach and affordability of insurance, the cooperation of states and employers, the promise of federal budgetary savings–will rise or fall on reformers’ ability to strengthen the act to ensure that it delivers on its promises. And, alas, playing offense is harder than playing defense in American politics, particularly in our current polarized climate.

Five years after passage, the ACA will be neither an endangered, crippled program nor a sweeping, uncontroversial success. Like Social Security in 1940, it will be a work in progress–one that could head in very different long-term directions: expansion and solidification, or erosion and fragmentation. How the first five years of the ACA are handled will shape the road taken. But, as Social Security’s history shows, the next five are likely to be even more critical.

The Implementation Imperative

Wilbur Cohen, the architect of Medicare, was fond of saying that successful social programs were “1 percent inspiration and 99 percent implementation.” As a brilliant administrator, he could be forgiven for a little hyperbole, especially since the exaggeration was in the service of an essential truth: Getting from good laws to favorable outcomes is no easy task. This is particularly so when laws lean heavily on the cooperation and partnership of multiple parts and levels of government and many private-sector actors with differing interests. In this respect, Cohen’s Medicare was a model of simplicity–a single national program automatically enrolling a defined population and dealing with a few key stakeholders, most notably hospitals and doctors, whose main interest was higher reimbursements.

By comparison, the ACA looks like a Rube Goldberg contraption. Its basic structure mixes state and federal responsibilities, competing administrative centers of authority, and public and private activities in a manner that can be charitably described as complex. The most Medicare-like aspect of the original legislative package was the so-called public option–a public insurance plan competing with private plans for the business of nonelderly Americans, an idea I have long championed. However, the public option was stripped from the legislation in the Senate to batten down wavering Democratic votes and overcome a GOP filibuster. A simple, popular element that could have provided a major tool of cost containment was lost.

The simplest way to describe the new law is that it creates three pillars of coverage, supported by a foundation of regulations and spending. The first pillar is an expansion and upgrade of Medicaid, the existing state-run program providing health coverage to the less affluent. Even though the federal government will finance virtually all the expansion, states will have to reach those who are eligible and ensure that coverage on paper means in fact that doctors and hospitals will be willing to take often-penurious payments–something many states do poorly now and will continue to do poorly after reform.

The second pillar is the creation of new health-insurance “exchanges” that will allow small employers and Americans who do not receive employer-based coverage to choose among regulated private plans, with much of the premium expenses for middle- and low-income Americans borne by the federal government. The plan is to have these exchanges set up by the states by 2014, but the federal government will establish them directly if states do not. Moreover, states can also establish them in cooperation with other states, an option that might be attractive in less populated regions or where multi-state metropolises exist. And the federal government will contract with at least two private health plans directly–at least one a nonprofit–to provide coverage on a nationwide basis. These national plans will also be offered through the exchanges.