A new survey by the Kaiser Family Foundation finds growing support for the health insurance reform law enacted by President Obama in March. Fifty percent of Americans now view the measure favourably while 35% oppose it – 14% are unsure. Two months ago, 41% supported it; 44% didn't. I don't have to remind you how unpopular it was at the time of enactment.

So, you might ask, why the change of heart? For starters, Armageddon never happened. But mainly, the disinformation campaign emanating from the healthcare industry and conservative establishment quietened, allowing the public to think about the Affordable Care And Patient Protection Act more clearly.

Let's remind ourselves what this law does. It protects consumers from being denied care by insurance companies. It extends coverage to 32 million Americans. It allows small businesses and individuals to pool together in exchanges. It permits young adults to remain on their parents' plans until age 26. And the nonpartisan Congressional Budget Office projects that it does all of this while reducing the deficit by $143bn in ten years and by $1.2tn in two decades.

America's relationship with major social programmes is best understood through a historical lens. In this context, the trajectory of the Affordable Care Act is normal and expected – expansive safety net legislation is unfailingly met with fierce resistance upon inception, but if and when it passes, the public tends to warm up to it.

Flash back to the debate over Medicare in the 1960s – whose enactment enjoyed its 45th anniversary on Friday. The public was quite evenly divided for and against it, while conservatives pressed fears about "socialised medicine". Embodying the Republican sentiments of the time was Ronald Reagan, who warned that if this bill passes, "you and I are going to spend our sunset years telling our children, and our children's children, what it once was like in America when men were free." Oops. Medicare is overwhelmingly popular today, and most Republicans are loth to admit they ever opposed it.

Go back another 30 years, just before the passage of Social Security, and you'll see a similar landscape. "Never in the history of the world has any measure been brought here so insidiously designed as to prevent business recovery, to enslave workers and to prevent any possibility of the employers providing work for the people," said Republican Congressman John Taber in 1935. "The lash of the dictator will be felt," added his GOP colleague Daniel Reed. How'd that work out? Well, even George W Bush – who as president tried and failed to privatise Social Security – felt the need to call it "the single most successful programme in government history," during his 2000 campaign.

You get the point. This is how the narrative unfolds – no major social legislation is initially without its share of powerful opponents, who tell horror stories about big government and socialism to try and stop it in its tracks. But once it muscles through, it usually winds up becoming a fact of life. Even now, when conservatives are invoking deficit fears to try and cut Social Security and Medicare, House GOP leader John Boehner has declined to endorse the closest thing that exists to a Republican agenda, which happens to reduce the scope of both programmes.

Will America learn its lesson next time such reforms are considered? Probably not. The forces of demagoguery and the clout of industry, combined with a largely apathetic public, are usually too strong to overcome. It took a historic depression to pass the New Deal. It took a vast progressive uprising to achieve the Great Society. And now, it took a shattered economy, a Democratic presidential landslide and massive Congressional majorities to achieve near-universal healthcare.

Of course, like Medicare and Social Security, the Affordable Care Act will need to be tweaked down the road and require effort to be implemented right. And even the Republicans making noises about repeal know it's here to stay. House Liberals are already seeking to bring back the public option, which could be the missing ingredient for cost control and is projected to further cut the deficit.

Democrats are celebrating Medicare on this anniversary week. In another 45 years, they'll probably be doing the same with the Affordable Care Act – by which point it should be woven into the fabric of American society, and no ambitious politician or political party will have the guts to admit they ever opposed it.