For a half-century I’ve been hoping America could achieve something like Medicare for All. But in the upcoming New Hampshire primary, I won’t be voting for candidates who put it at the top of their domestic agenda.

Let me explain why. First, you should know something about me. I’ve spent my career – 50 years and counting – reporting on medicine and health, first for The Boston Globe, then for NPR. I’ve covered many noble attempts to extend health care to all.

I’ve documented big-time failures, such as the political collapse of a promising bipartisan health plan under Richard Nixon (it actually looked sort of like Obamacare). And the 1992 repeal of Michael Dukakis’s sweeping legislation that was supposed to guarantee health coverage to every Massachusetts citizen. Most spectacular was the collapse of the Clintons’ ambitious Health Security Plan in 1994.

I’ve also reported on meaningful, if incremental, progress. That included the so-called Romneycare plan, a landmark 2006 Massachusetts law that served as the template for the Affordable Care Act/Obamacare four years later. Along the way, I wrote a book on Germany’s health system, about which more below.

This long history teaches two big lessons.

First, how to fix health care is very complicated! Our current chaotic, irrational, unfair system is about as wonky a subject as you could try to get your mind around. That, of course, is the appeal of Medicare for All, which promises to replace the chaos with a simple, nationally uniform, transparently fair system. I get that.

But Medicare for All will also force us into fierce and tortured debates about how to transition from here to there, what impact it would have on our Rube Goldberg health care system and how it will affect everyone who depends on it. In these debates facts rarely carry the day, take my word. Don’t expect that to change in whatever Great Health Care Debate looms in 2021.

That gets me to Lesson Two: It is very easy to spook the 176 million Americans who currently have private health insurance, not to mention 110 million others covered by various government-funded plans who stand to be affected by big change.

We’ve seen this kind of spook work over and over again. During the debate over the Clintons’ health plan, a TV ad campaign sponsored by the Health Insurance Association of America deftly planted seeds of doubt. Viewers saw a fictional couple named Harry and Louise angst-ing over the Clinton plan at their kitchen table. Once the 1,000-page proposal got to the Senate floor, it took Majority Leader Bob Dole all of a couple of days to kill it, mainly by wielding the charge that it would take away Americans’ choice of health plan, doctor and hospital.

In fact, the Clinton plan would have expanded Americans’ menu of health care options. Most people in employer-sponsored health plans have a limited choice of health plans, or no choice at all; the Clinton plan would have let people themselves (not their employers) choose among a range of approved plans, boosting competition in the process.

The Clinton plan was widely expected to pass. When Bill Clinton campaigned in 1990 on a promise to fix America’s “badly broken health care system,” public support for major health reform was at a 40-year high. But in post-Reagan America, public faith in government was at an historic low. And the great majority of Americans who had employer-sponsored health insurance were very nervous about anything that might disturb their coverage arrangements.

All this is worth keeping in mind in 2020.

Also worth remembering is that one of the first compromises President Obama had to make in 2010 to secure House passage of the Affordable Care Act (by a margin of only seven votes) was to jettison the idea of opening up Medicare as another option for all Americans. The insurance industry wouldn’t stand for it.

So here we are, a decade later. Major reform of the U.S. health care system is once again at or near the top of many voters’ domestic to-do lists. And the leading proposal is a big leap beyond Obamacare, all the way to Medicare for All, replacing private insurance.

Ain’t gonna happen that way. There are many compelling arguments to be made for a single-payer health care model. And I’d love to be proved wrong. But I just don’t see our elected representatives jumping that far, that fast. There are too many opportunities for spooking – about the cost, about the impact on our $3.4 trillion health system, about disruption of most Americans’ health care, about a “government takeover” of something so close to every family’s basic needs.

At the same time, it’s striking that the non-starter proposal of 2010 – letting citizens “buy into” Medicare – has become the ho-hum “moderate” Democratic proposal of 2020. This is progress – potentially!

I’ve long believed the U.S. is destined to evolve toward universal health coverage – if we’re so lucky and wise – in a complicated and messy way that builds on our public-private system. That’s why, in 1991, when debate over the Clinton plan was revving up, I spent a year studying Germany’s health system. I’ll spare you the details, but suffice it to say that Germany has the world’s oldest, and arguably most successful, universal care system.

We’re not going to have a German system. For one thing, Germans have a deep-seated belief in what they call solidarity – a we’re-all-in-this-together ethic that holds the young must subsidize the old, the well pay for the sick, single people support family coverage. In contrast, many Americans don’t seem to get the fundamental concept of insurance – a different term, more or less, for the same thing.

But consider this: Germany’s system evolved out of private (mostly nonprofit) insurance plans. To this day, it’s more “private” than in the United States, where the government already pays at least 60% of our total health tab. Despite its complexity, Germany’s administrative costs are kept low because, by law, everybody has the same benefits; there’s far less opportunity for insurers and care providers to game the system.

It’s possible, and maybe likely, that letting Americans of all ages choose to buy into Medicare would accelerate our final push toward health care for all. We might end up with a single-payer plan. Or we could eventually grow a system that, like Germany’s, gets the job done in a more complicated way – but is less crazily complex, fairer and more manageable than what we have now.

When you vote on Feb. 11, think carefully about which candidates are most likely to get us to that elusive goal.

(Richard Knox lives in Sandwich.)