Love it or hate it — and he hates it — the 2010 Affordable Care Act has changed the health insurance landscape, U.S. Sen. Bill Cassidy, R-La., says.

That’s a reality, Cassidy says, that Republicans must recognize as they grapple with a response to a pending U.S. Supreme Court decision that could gut the law, which is more popularly known as “Obamacare” and ranks as the No. 1 legislative achievement of Democratic President Barack Obama.

“What folks don’t realize,” he said at the conservative Hudson Institute nonprofit advocacy group last month, “is that ‘Obamacare’ has scorched the earth.”

One conservative interpretation of that claim is that “Obamacare” has created a class of federal-government dependents loath to see their benefits taken away. One of those benefits lies at the heart of the legal case: the subsidies to low- and middle-income Americans that help them pay for the insurance the law requires them to buy.

There are 6 million of those subsidized insurance-buyers — including nearly 200,000 in Louisiana — in the three dozen states that did not set up their own “Obamacare” insurance exchanges but instead rely on the federal exchange. The plaintiffs in the court case maintain a phrase in the law renders the subsidies in those states illegal. The Obama administration argues otherwise. A ruling is expected by the end of the month.

The ACA passed Congress without a single vote from Republicans, and they have attacked it ever since. But there is consternation in their ranks about the political fallout if 6 million Americans lose their ability to buy health insurance and direct their anger at Republicans.

Republican U.S. Sen. Ron Johnson, of Wisconsin, has proposed extending the subsidies through August 2017 — by which time, the Republicans hope, one of their own will occupy the White House as a result of the 2016 election, and the new president and Congress will have devised a comprehensive alternative to “Obamacare.”

But as Cassidy recognizes, the new order created by “Obamacare” goes well beyond subsidies and in ways that pose a profound challenge for his fellow party members.

“Obamacare” has raised the bar for health policy and set higher expectations for what it ought to include.

A ready example is the requirement that children can remain covered by their parents’ insurance up to age 26. That was cast in law by the ACA and is now pretty much accepted as a given, including by Republicans.

More problematical for them is another feature now widely regarded as inviolate: that no one should be denied coverage because of a pre-existing medical condition or the onset of an illness.

Patients in those categories are costly to insure. If a company insured only unhealthy people, it would need to charge astronomically high premiums to stay in business.

The solution is to ensure healthy people, too, so their premium payments, which exceed the cost of treating them, help to cover the unhealthy and allow more reasonable rates for everyone.

But if healthy people forgo coverage altogether, costs go up for the less healthy people left in the pool of insured, forcing more to the sidelines, triggering higher premiums for the remaining even less-healthy people who must carry insurance, and so on, in what’s known as a “death spiral” of ever-escalating premiums.

“Obamacare” answers that relentless arithmetic with mandates for people to buy and employers to provide insurance, creating a big pool. But those mandates are the most odious element of the law for many conservatives.

“It is an American value to be about freedom,” Cassidy said May 19 at Hudson. “It is a foreign value to tolerate government coercion.”

But Cassidy, a gastroenterologist who for decades treated uninsured patients at public hospitals in Baton Rouge, understands the arithmetic. His Patient Freedom Act aims to solve the riddle by essentially converting the subsidies to grants that people could spend on health care or insurance premiums.

Mandates are eliminated, but to enlarge the coverage pool, anyone lacking insurance automatically would be enrolled in a default plan.

The default-plan enrollees could opt out and go without insurance altogether if they wish. But most of them won’t bother to unenroll, Cassidy says, predicting a 95 percent participation rate.

Liberal critics are skeptical. But, Cassidy said, “If we don’t have this plan, after saying we would have a plan to replace ‘Obamacare,’ we will be judged harshly.

“With this plan, I think we will be judged well.”

Gregory Roberts is chief of The Advocate Washington bureau. His email address is groberts@the advocate.com, and he is on Twitter, @GregRobertsDC. For more coverage of national government and politics, follow The Advocate Politics Blog at http://blogs.theadvocate.com/politicsblog/