Don Berwick, the administrator in charge of Medicare and Medicaid, was having dinner in Dupont Circle not long ago with five of his predecessors when the conversation veered to how long he could keep his job.

In the realms of health care, his is a pivotal role: overseeing two entitlement programs that insure nearly one in three Americans, sheperding the profound insurance changes spurred by the new health-care law and serving as chief cheerleader for better care at lower cost.

A pioneer in improving medical quality, but a neophyte in Washington politics, Berwick ran into a buzz saw of Republican opposition over old academic writings when President Obama chose him for the task 16 months ago. A year ago this week, the president slid him into the job without Senate confirmation while Congress was out of town. The “recess appointment” installed Berwick at the helm of the Health and Human Services’ Centers for Medicare and Medicaid Services. But, unless the Senate acts, he cannot stay beyond December.

And so, during the April dinner, he and the former administrators, his “brain trust,” addressed the awkward but central issue: Was there any chance for a confirmation hearing now?

From all five around the table, Democrats and Republicans alike, “the feedback he got was sort of, ‘forget it,’ ” recalled Bruce Vladeck, the Medicare and Medicaid chief under President Bill Clinton and one of three people there who recounted the conversation. The effort would be futile, they said. “Don’t ruin your legacy and make a fight out of it,” one person told him.

As a result, unless something unexpected happens, this 64-year-old pediatrician and Harvard Medical School professor is racing to carry out one of the nation’s biggest health-care jobs with a timer ticking down the months.

Assuming he leaves at the end of the year, Berwick will have overseen large portions of the government’s work on crucial scaffolding for the 2010 law overhauling the health-care system — including regulations due out this week for insurance exchanges that states are expected to create by 2014, as well as rules scheduled for later this year year defining the medical services that health plans in exchanges must cover.

At the same time, Berwick’s departure would remove an intellectual architect of many ideas imbedded in the law he is working to implement — to the dismay of the law’s allies and the delight of its critics.

Berwick has been trying to inject into the sprawling agency a set of big-picture ideas about innovation in health care that he honed as leader of a nonprofit organization, the Institute for Healthcare Improvement, that he founded in Cambridge, Mass., 20 years ago.

His ideas go back to the mid-1980s, when he was vice president of the Harvard Community Health Plan, an HMO. He and the staff felt helpless, he recalled, because the quality of care was static, and they did not know how to make it better. “I tried to quit,” he said. Instead, his boss made an unusual offer: Why not travel the country to examine other leading industries to figure out how to improve?

Berwick visited Gillette, Sheraton hotels, AT&T and NASA — and came away with an insight about industrial systems that could be imported to health care. “Every system,” he has told students he taught over the years, “is perfectly designed to achieve exactly the results it gets. . . . If you want a car that goes faster, you need a different car.”

In the same way, he realized, health care has performance standards akin to a car’s top speed: how often patients die, how frequently they suffer medical complications, how long they must wait for an appointment, how satisfied they are. The task was to find changes that would improve each one.

For two decades, he and institute colleagues have worked with health-care institutions throughout the United States and internationally, coaching them on how to reduce medical mistakes and improve patients’ outcomes. He also helped write a pair of studies by the prestigious Institutes of Medicine that have had wide impact on thinking about health-care quality and patient safety.

At CMS, he has been trying to instill his views about systems, management and medical quality, holding seminars for staff members, urging them to collaborate with different parts of the agency and bringing in speakers. He is encouraging everyone there to spend a half-day at a hospital, doctor’s office or other medical site to ask the question, “What do we do that affects your work, and what can we do that will help?”

Although he had interacted with official Washington for years, Berwick acknowledged that, when he arrived, “I didn’t really know much about how government works. I had a citizen’s view.” Gail Wilensky, a friend and admirer who ran Medicare and Medicaid under President George H.W. Bush, said: “Don is not the most political of people” and has had “some amount of naivete as a result.”

The agency has been widely criticized, for instance, for rules it proposed this spring to create within Medicare “accountable care organizations” — a new form of managed care relying on teams of doctors and hospitals to improve the coordination of patients’ care and spend less money. Even health-care executives who agree with the basic idea have criticized many of the specifics. Berwick said the agency will alter the rules before they become final.

He has trained his focus most intensely on patient safety and better ways to organize health care. This spring, CMS announced a Partnership for Patients — an aspect of the law, but also vintage Berwick — that is giving out $1 billion to cut down on hospital infections and readmission of patients for whom things go wrong. So, far 1,800 hospitals have volunteered to take part.

Even some of his Democratic friends say that Obama placed him in an awkward spot. First, the president waited more than a year to name someone to the critical CMS administrator’s job, then he chose Berwick at a time of great political hostility, weeks after congressional Democrats pushed through the health-care law that Republicans already were vowing to dismantle.

Republicans focused, for instance, on academic writings in which Berwick had praised aspects of the British National Health Service; Republicans said his views were tantamount to support for rationing and socialized medicine.

The controversy, Berwick said, caught him by surprise. But in retrospect, he said, “I wouldn’t take a word back.. . . My general reaction has been almost as if these people are talking about somebody else.”

Every nation, he said, must find a health-care system that fits it best. As for the rationing charge, he said: “Every bone in my body as a physician, even as a person, is to get everything they want and need to help them at every step. I have gone to the mat to get a last-ditch bone marrow transplant for a child with leukemia. . . . And they are telling me I’m a rationer? They haven’t met me.”

In January, Obama renominated Berwick, but the GOP criticism persists. “Unless his thoughts on health care have completely changed, I will once again oppose his nomination,” said one of his chief critics, Sen. Pat Roberts (R-Kan.), who reiterated his allegation that the administrator “has a record on rationing care.”

In March, 42 GOP senators — enough to block his confirmation — signed a letter, urging the president to withdraw Berwick’s name. Senate Finance Committee Chairman Max Baucus (D-Mont.), a key figure in his confirmation prospects, said publicly that the Republican opposition was too strong to move forward.

Berwick approaches the discord with a certain detachment. “This will sound a little weird,” he said, “but when you are a pediatrician or a father, you always are saying, what is this kid’s strength. . . . Even the people that disagree the most, they bring something to the table.”

Wilensky said, “I think basically he understands the handwriting on the wall. But, like many of us, he has a portion of him that hopes somehow it will come out differently.”