In today’s world of 24-hour news and 15-second sound bites, every policymaker knows that managing the message is the key to winning over the public. So why has the messaging on behalf of one of the most dramatic public reforms of our lifetimes, the federal Affordable Care Act, been so incompetent?

Provisions of the 2010 healthcare reform have already changed the lives of millions of Americans for the better. It has brought insurance coverage to more than 2.6 million previously uninsured young adults, cut prescription costs by a total of $3 billion for millions of seniors, eliminated co-pays on preventive services such as child immunizations and cancer screenings and eliminated annual and lifetime claims caps for more than 80 million policyholders.

When its broadest provisions are triggered in 2014, millions more Americans will be relieved of the threat that their insurer can dump them or jack up their premium to unaffordable heights just because they’ve fallen ill or been injured.

“No longer will people be bankrupted because they have a bad gene or a bad traffic accident,” says Jonathan Gruber, a health economist at MIT who helped fashion the pioneering healthcare reform act in Massachusetts.

Did you know any of that? If so, you’re in the minority. Only 39% of respondents to a Kaiser Family Foundation poll released this month thought they had enough information to understand how the law would affect them personally — and that figure had declined over the last year. Only 1 in 4 respondents knew that the act already has eliminated co-pays for preventive care and lowered prescription costs for Medicare members.

On the other hand, most of the provisions above win overwhelming public support when they’re explained to respondents and polled individually. Still, poll respondents with any opinion at all on the measure remain evenly split about it, according to a Kaiser Family Foundation survey released in December.

Blame for the knowledge gap belongs chiefly to the act’s supporters, who have consistently failed to stand up for their own accomplishment, as was evident during the 2010 congressional campaign, when they allowed opponents to define the act for them. The harvest was all that ridiculous talk of “death panels” and a government takeover of healthcare.

This should worry policymakers as the 2-year-old law faces two crucial tests. Arguments before the Supreme Court on the measure’s constitutionality are scheduled for this week. Even more important, the act is sure to be the outstanding political football of the coming presidential election (despite the endlessly masticated fact that the putative Republican front-runner, Mitt Romney, implemented the state-level model for the federal law as governor of Massachusetts but says he opposes the federal version).

What’s unfortunate is that the political battle is certain to feature continued sophistry by reform opponents — “selling fear instead of facts,” as Gruber puts it in a new book, “Health Care Reform: What It Is, Why It’s Necessary, How It Works,” which attempts to explain the act in the format of a graphic novel.

In recognition of the old saw that a lie can get halfway around the world before the truth can get its boots on, here are some healthcare reform facts, already shod.

Start with coverage of younger persons. The 18-26 age group has tended to be overrepresented among the uninsured — 28% were uninsured in 2009, according to a Gallup survey. In part this happens because people just embarking upon their careers find it harder to afford coverage, may not have families to worry about and as “young invincibles” think they can safely go without coverage.

As a result of a reform act mandate that offspring as old as 26 could be covered by their parents’ policies, the uninsured rate in this cohort has plummeted to less than 25% — the only such decline since 2010 marked in the Gallup survey. That’s a tangible benefit not just for younger people who can now afford insurance, but also for many parents who had continued to foot their kids’ bills for individual insurance.

The billions in savings in prescriptions from seniors comes from the act’s closing of the “doughnut hole” in Medicare’s Part D prescription coverage, which subjected enrollees to unexpected out-of-pocket expenses after they reached a given spending level.

The act already has eliminated a loophole that allowed insurers to deny coverage for children with preexisting conditions, and has provided federal funding for states to provide coverage for adults with chronic conditions who were denied insurance in the private market. This is a bridge to 2014, when all such exclusions will be outlawed; like many such provisions, it applies chiefly to non-group and non-employer-provided health insurance, where the most flagrant consumer abuses appear.

The effects of many such regulations are already visible in California, which has been ground zero of the insurance crisis. California’s uninsured rate runs four to five percentage points higher than the national rate, in part because of its preponderance of small employers and big-box retailers such as Wal-Mart, which traditionally stick government and other coverage providers with the burden of insuring its workers. The state’s individual insurance market is the nation’s biggest, encompassing more than 2 million people whose lives have been at particular risk from insurance practices such as cancellation of coverage for sick or injured customers.

The reform act has greatly expanded the state’s ability to offer coverage to those who have lost their insurance by funding a new program that today covers 8,600 high-risk Californians at reasonable premiums, according to Anthony Wright, executive director of Health Access California, which last week issued a report card on the act’s effects in the state. The study calculated that the act has brought coverage to 370,000 low-income Californians through federal funding for county programs, allowed 355,000 young persons to stay on their parents’ plans and provided 9 million Californians with new consumer protections.

“We’re pretty sure that people don’t want to go back to a world where they don’t know if their insurance will cover them,” Wright told me. “But until they get sick, people may not necessarily realize what the improvement is.”

There are even signs that the act may be helping to moderate premium increases. A survey by the benefits consulting firm Mercer projects the rise in health benefit costs in 2012 to be the lowest in 15 years. Figures from CalPERS and the U.S. Bureau of Labor Statistics similarly point to a slowdown in cost growth, although the reform act’s influence on the trend is hard to gauge.

The biggest gap in public understanding applies to the act’s provision requiring Americans to carry health insurance beginning in 2014, whether through the government, through their employers or purchased from a so-called exchange that will oversee the commercial market — the so-called individual mandate.

Polls show the mandate is the act’s least popular provision, and it’s at the center of the challenge before the court. But it’s impossible to overstate how central the individual mandate is to the Affordable Care Act. Without it, the reform’s crucial companion provision eradicating exclusions for preexisting conditions will be financially untenable for the insurance industry. That’s well understood by reformers, insurance executives, and responsible conservatives — Romney himself has consistently defended the principle as he applied it in Massachusetts.

Conservative analysts Douglas Holtz-Eakin, a former director of the Congressional Budget Office, and Vernon Smith, a Nobel economics laureate at Chapman University, observed last week in a Wall Street Journal op-ed that the reform act would cost insurers $360 billion over 10 years without the mandate, but produce a gain of $6 billion with it. For insurers, they concluded, “the benefits of the individual mandate ... are projected to balance, nearly perfectly, the costs” of other regulations in the reform act.

The failure of the act’s supporters to get these complicated concepts across to the public has poised health insurance reform on the knife edge between triumph and tragedy — triumph if it survives Supreme Court review and the November election, tragedy if it does not.

Making its virtues plain was never going to be easy. “In today’s political climate, once you have an explanation that takes more than two sentences, you’re screwed, because someone else will have a one-sentence lie,” says Gruber. “This is about getting people to understand the law. We’ve just got to get it in place, let Americans feel the benefits, then they’ll like it.”

Michael Hiltzik’s column appears Sundays and Wednesdays. Reach him at mhiltzik@latimes.com, read past columns at latimes.com/hiltzik, check out facebook.com/hiltzik and follow @latimeshiltzik on Twitter.