Don’t repeal and replace the ACA. Retain and repair it.

When President Obama was in office, Republicans made a mantra of their call to “repeal and replace” his signature health care program. But now that they are actually in position to do something, they’re flummoxed.

They have no plan for a replacement anywhere near as robust as Obamacare. They can’t even agree on what a significant rollback would look like.

So might we suggest an alternative approach? It starts by treating Obamacare the same way that a doctor would treat a patient: First, do no harm.

Republicans know they would pay a huge political price if they killed Obamacare and left millions of people without health coverage, including for addiction treatment in the midst of an opioid epidemic. To avoid that, the Republicans should adopt a new mantra. Rather than “repeal and replace,” they should preach “retain and repair.”

Obamacare is very complicated, but two facts are clear. One is that it has provided insurance coverage to 20 million people while having a benign effect on overall health care prices. The other is that it is in trouble in some states, where too few young people (and too many unhealthy people) are signing up. That’s causing insurance companies to hike premiums and deductibles, or pull up stakes altogether.

Even without any action by Congress, the Trump administration could take several steps to undermine the Affordable Care Act and several to shore it up.

Waiving or watering down the mandate that all individuals have insurance would be devastating. Eliminating the mandate would make it all but impossible for insurers to offer coverage to people with pre-existing conditions and to allow children to stay on their parents’ policies until age 26, two of the most popular features of the ACA.

One reason too few young people sign up is that Congress set the penalties for not having coverage too low. If those penalties are reduced or eliminated, healthy people would have little incentive to buy insurance until they get sick.

On the other hand, the Trump administration is said to be considering some ideas that would meet the do-no-harm standard and might actually help.

One is to slightly raise insurance costs for people near retirement while lowering them for young people. Administration officials are also said to be considering cutting back on some grace periods that insurance companies say are being gamed by savvy customers.

One idea would clamp down on people who are late on their payments. Another would tighten the requirement that people document a life event (such as marriage, birth or change in employment status) before being allowed to enroll outside of the open enrollment period.

These ideas could result in lower premiums and persuade insurance companies to stay in the exchanges. They also reflect what Republicans say they would like to do legislatively if they can ever muster consensus and votes.

Obamacare — or whatever it is to be called going forward — has many things working for it. If Republicans want to show they can govern, their best course is to fix the things that are working against it.