MASSACHUSETTS HAS some of the best doctors, nurses, and other caregivers in the world. Yet our national health care system costs too much and covers too few. Climbing costs put basic coverage beyond the reach of millions. This is economically unaffordable and a moral disgrace.

Promoting affordable, quality health care has been one of my top priorities as attorney general, and it will be a top priority if I serve in the Senate. National efforts should draw on lessons that we have learned in Massachusetts.

The good news is that our reforms here show that it is possible to provide insurance to almost everyone. We have done so by building consensus with the business community, doctors and hospitals, insurers, and most of all, consumers.

Our state’s experience also...