It’s easy to understand why Republicans wish health reform had never happened, and are now hoping that the Supreme Court will abandon its principles and undermine the law. But it’s more puzzling . and disturbing . when Democrats like Charles Schumer, senator from New York, declare that the Obama administration’s signature achievement was a mistake.

In a minute I’ll take on Mr. Schumer’s recent remarks. But first, an update on Obamacare . not the politics, but the actual policy, which continues to rack up remarkable (and largely unreported) successes.

Earlier this week, the independent Urban Institute released new estimates of the number of Americans without health insurance, and the positive results of Obamacare’s first year are striking. Remember all those claims that more people would lose coverage than would gain it? Well, the institute finds a sharp drop in the number of uninsured adults, with more than 10 million people gaining coverage since last year. This is in line with what multiple other estimates show. The primary goal of health reform, to give Americans access to the health care they need, is very much on track.

And while some of the policies offered under Obamacare don’t offer as much protection as we might like, a huge majority of the newly insured are pleased with their coverage, according to a recent Gallup poll.

What about costs? There were many predictions of soaring premiums. But health reform’s efforts to create meaningful competition among insurers are working better than almost anyone (myself included) expected. Premiums for 2014 came in well below expectations, and independent estimates show a very modest increase . 4 percent or less . for average premiums in 2015.

In short, if you think of Obamacare as a policy intended to improve American lives, it’s going really well. Yet it has not, of course, been a political winner for Democrats. Which brings us to Mr. Schumer.

The Schumer critique . he certainly isn’t the first to say these things, but he is the most prominent Democrat to say them . calls health reform a mistake because it only benefits a minority of Americans, and that’s not enough to win elections. What President Obama should have done, claims Mr. Schumer, was focus on improving the economy as a whole.

This is deeply wrongheaded in at least three ways.

First, while it’s true that most Americans have insurance through Medicare, Medicaid, and employment-based coverage, that doesn’t mean that only the current uninsured benefit from a program that guarantees affordable care. Maybe you have good coverage now, but what happens if you’re fired, or your employer goes bust, or it cancels its insurance program? What if you want to change jobs for whatever reason, but can’t find a new job that comes with insurance?

The point is that the pre-Obamacare system put many Americans at the constant risk of going without insurance, many more than the number of uninsured at any given time, and limited freedom of employment for millions more. So health reform helps a much larger share of the population than those currently uninsured . and those beneficiaries have relatives and friends. This is not a policy targeted on a small minority.

Second, whenever someone says that Mr. Obama should have focused on the economy, my question is, what do you mean by that? Should he have tried for a bigger stimulus? I’d say yes, but that fight took place in the very first months of his administration, before the push for health reform got underway. After that, and especially after 2010, scorched-earth Republican opposition killed just about every economic policy he proposed. Do you think this would have been different without health reform? Seriously?

Look, economic management is about substance, not theater. Having the president walk around muttering “I’m focused on the economy” wouldn’t have accomplished anything. And I’ve never seen any plausible explanation of how abandoning health reform would have made any difference at all to the political possibilities for economic policy.

Finally, we need to ask, what is the purpose of winning elections? The answer, I hope, is to do good . not simply to set yourself up to win the next election. In 2009-10, Democrats had their first chance in a generation to do what we should have done three generations ago, and ensure adequate health care for all of our citizens. It would have been incredibly cynical not to have seized that opportunity, and Democrats should be celebrating the fact that they did the right thing.

And one related observation: If more Democrats had been willing to defend the best thing they’ve done in decades, rather than run away from their own achievement and implicitly concede that the smears against health reform were right, the politics of the issue might look very different today.