Of course, it won’t be that easy. Critics will say her requirement on employers is really a tax rather than a “mandatory contribution,” as her campaign labels it. Others will ask whether, politically or constitutionally, states can be asked to finance a federal program even when Medicaid and S-CHIP are discontinued. For both employers and states, however, the Warren plan promises big savings relative to their forecast health spending. More important, it shifts the focus to the most significant issue: how we can get from here to there.

In the Medicare for America approach that I’ve advocated, everyone would be guaranteed coverage, but private workplace plans could continue. The idea is that the system would evolve toward universal Medicare if employers and individuals saw the expanded Medicare program as a better deal than private insurance.

The framework from the Warren campaign takes a different approach. Essentially, it envisions that employers will stop buying private insurance and instead finance Medicare for their workers. At first, this would basically lock in the current distribution of spending. But over time, contributions could be evened out across employers, so the system won’t penalize those who were already helping out their workers, or those workers themselves (who bear the cost in lower wages).

In short, the Warren approach sacrifices some degree of rationality and equity to make the transition more politically realistic — which, given how far the system now is from rational or equitable, seems a reasonable trade-off. Further concessions will surely be needed, especially to address the concerns of those who have private insurance through their employer or Medicare (a third of beneficiaries, after all, are enrolled in private plans through Medicare Advantage).

But the message of Ms. Warren’s new plan is that American health care is so costly because it is so inefficient and because it is so lucrative for a narrow segment of American society. By showing how broad the benefits could be if costs were really tackled, she is also outlining a political approach fundamentally different from the strategy followed by President Barack Obama and his allies, who cut expensive deals with the medical-industrial complex and did all they could to minimize disruptions to the present system.

Ms. Warren instead is picking a fight with all the big interests that now depend on the system’s high prices and administrative overheads. As she sees it, the nation can’t afford to buy off the industry again to squeeze through legislation. It has to overcome resistance by promising something clear and simple that Americans can rally behind. Whether she’s right about that or not, her challenge to the narrow framing of the issue seems certain to shake up a familiar debate — and maybe even change it altogether.