The Affordable Care Act, like any major statute, surely could use adjustments. For example, the insurance subsidies were probably set too low initially. The Obama administration’s decision to allow more people to stay on their old plans than originally expected may also have narrowed the new pool of insurance customers in ways that contributed to premium hikes. The Republican-controlled House never provided any additional implementation money after the initial appropriation set forth in the Affordable Care Act itself, forcing the Department of Health and Human Services to scrounge for needed funds.

A caretaking Congress would have fixed what wasn’t working. Instead, opponents did everything possible to shut off all the A.C.A.’s financing — starvation intended to wreak havoc in the insurance markets and to make it falsely appear that the A.C.A.was collapsing because it was just bad policy.

The irony is that the A.C.A. was vulnerable to this strategy because the Democrats had tried to compromise with the Republicans in an ultimately unsuccessful effort to build bipartisan support for the law. If the Democrats had instead enacted a single-payer policy — such as Medicare for all — the entire health care system would have been in the hands of the federal government, instead of dependent on the states and private insurers.

Now the Republicans find themselves in a mess. The Affordable Care Act has brought health care to an estimated 20 million more Americans and has expanded services — including access to drugs and preventive screening — for many more. A good number of Americans, including Republicans and the president himself, say they like elements of the law. It’s not a coincidence that the Trump administration’s first proposed health care regulation was aimed at stabilizing the insurance markets.

Still, Republicans are using the Affordable Care Act’s so-called collapse as an argument for a much stingier law, one that would leave states responsible for paying many health care costs. Some conservatives are using the assault on the A.C.A. not to assail its novel insurance provisions — which many people like — but rather to grind an old ax against the entire Medicaid program, which was enacted in 1965 to help the poor.

As the Senate turns to its own bill, it still has time to preserve the parts of the Affordable Care Act that are working and, more importantly, strengthen those that could succeed with proper support. That would be responsible — and, indeed, is what should have happened all along.