By Ramesh Ponnuru / Bloomberg Opinion

Obamacare seems to be on more solid footing than ever. Not only did the Supreme Court turn back another big legal challenge to it, with a solid 7-2 majority; Republicans are hardly even talking about it, in spite of former President Trump’s needling on the issue.

The prevailing story about the Affordable Care Act’s endurance is that it is a tribute to the public’s aversion to risk. The main obstacle to getting it passed in 2010 was that too many people worried that it would upend their existing health-care arrangements. But after it was fully implemented, people feared a Republican replacement would disrupt their care. Under threat, Obamacare became popular. And so Republicans failed in their drive to undo the law in 2017.

All of that is true, which is why I’ve told that story a time or two myself. But Obamacare has gotten more secure for another reason: Over the years, it has shed some of its most objectionable features.

Start with its least popular one: the individual mandate. The first change came when the Supreme Court narrowly upheld it but, at the same time, reinterpreted it. Congress could not command Americans to buy health insurance, Chief Justice John Roberts explained in 2012, but it could levy a tax on people who didn’t buy it. In 2017, Republicans in Congress and President Trump set the tax at zero. The mandate was effectively dead.

The runner-up among controversial parts of the law was the Independent Payment Advisory Board, an unelected body that was supposed to be able to impose cost savings on Medicare. It’s the part of the law that inspired Republican charges of government-directed rationing and “death panels.” In a bipartisan deal in 2018, Congress and Trump killed the board before it ever did anything.

Opponents of Obamacare railed against its taxes while it was going through Congress. Some of them never got implemented, either. The “Cadillac tax” on expensive employer-provided coverage kept getting delayed and then had a bipartisan death in 2019. The medical-device tax was briefly imposed but then met the same fate.

The insurance exchanges that the law established are, on the other hand, still in place; but in much diminished form compared with what they were supposed to be. In March 2012, as President Obama was running for re-election, the Congressional Budget Office projected that 22 million people would be enrolled in the exchanges by 2020. By that time, though, fewer than half as many people had enrolled.

The exchanges became, to an extent, the functional equivalent of the high-risk pools that Republicans said they wanted as an alternative to the ACA. The chief Democratic objection to that idea, a reasonable one, was that Republicans would never provide sufficient funding to those pools. That has not been a problem for the Democratic version of the idea.

Two other components of Obamacare have prospered. Its ban on insurers’ discriminating against people based on their health status has always been popular, at least when the costs are not mentioned, and Republicans have generally been careful to say they favor keeping the policy or something like it. This popularity, and Republicans’ inability to explain how any alternative would protect sick people, helped doom their effort to replace the ACA in 2017.

The law’s Medicaid expansion has done more than any of its other provisions to increase coverage levels. Even after the Supreme Court modified the terms of that expansion in 2012, it offered states an attractive choice: Participate, and the federal government will cover almost all the costs. While conservative states have held out, their number has dwindled. Missouri and Oklahoma are the latest to flip.

How might the debate over Obamacare have gone if the program had started out the way it ended up? Most Republicans would have opposed it anyway as government overreach from their political opponents. I would have opposed it myself, preferring an alternative that relied less on regulation and centered on making renewable catastrophic policies affordable to all.

But the opposition would have had less material to work with. Neither ideology nor partisanship kept 40 House Republicans from voting to expand the Children’s Health Insurance Program early in Obama’s term, and a modified Affordable Care Act might have both polled better and won over some of them. And without the individual mandate, two of the three Supreme Court showdowns would have been completely avoided.

This scenario could not have happened back when Obamacare was drafted and enacted because so many people on all sides thought the individual mandate was crucial to the success of the rest of the law. But it would be a mistake to look at this history and conclude simply that voters are fickle. Public opinion on Obamacare changed; but so did Obamacare.

Ramesh Ponnuru is a Bloomberg Opinion columnist. He is a senior editor at National Review and a visiting fellow at the American Enterprise Institute.