DESPITE A frenzied campaign by the White House and Speaker Paul D. Ryan, House Republicans failed to vote on the American Health Care Act on Thursday. So much the better: A badly flawed bill that in its original conception would have done far more harm than good got steadily worse as the GOP leadership tried to buy conservative support.

The AHCA underwent several major revisions this week that lawmakers had little time to process. Then, in their determination to keep to their vote schedule, Republican leaders discussed adding a massive health-care regulatory rollback designed to attract votes from the ultra-conservative House Freedom Caucus — changes that the Congressional Budget Office (CBO), the nation’s chief legislative scorekeeper, would have been unable even to fully analyze before a Thursday vote. In the process, GOP leaders threatened to commit the sort of legislative malpractice Republicans had accused Democrats of perpetrating in passing Obamacare seven years ago: rushing through a far-reaching reform without any buy-in from the other party and without giving lawmakers, let alone the public, a fair chance to evaluate its effects.

House Republicans might still make irresponsible hypocrites of themselves by voting on the measure Friday or early next week. Instead, they — and President Trump — should take a deep breath.

The longer the GOP bill has been on the table, the clearer its disastrous implications have become. First was a CBO report on the initial draft, finding that it would result in 24 million more people without health coverage within a decade — and that it would concentrate the pain on the aging and the low-income. A rollback of Medicaid would have left many extremely vulnerable people at the mercy of a market that was unlikely to serve their needs. Meanwhile, upper-income people would have received a tax cut.

Though Republican leaders decided to devote more money to helping aging people purchase insurance, it was unclear as of Thursday whether that would increase enrollment, let alone the quality of insurance that older and poorer buyers would be able to afford.

Rather than waiting for the picture to clear up, GOP leaders discussed even larger changes aimed at mollifying House conservatives. One would have repealed Obamacare’s “essential health benefits,” which require that insurers cover things such as prescription drugs, preventative care, addiction treatment and maternity services. Without these rules, the individual health-care market would return to its pre-Obamacare Wild West days — when insurers often sold flimsy policies designed to protect them from paying for their customers’ major health problems — except under the GOP bill, the federal government would also subsidize the purchase of skimpy plans. People who wanted to buy comprehensive coverage would struggle to find insurers willing to sell it to them, because no sane insurance company wants to attract sick patients. Even this desperate move failed to attract enough support in time for a Thursday vote.

Obamacare could use some reforms. But neither the public nor the actual state of the health system demands a destabilizing repeal. Thursday’s setback provides Mr. Trump with the opportunity to adopt a new course, moving away from intransigent conservatives and pragmatically working with Democrats as well as Republicans to improve the health-care system without depriving millions of people of coverage.