In the midst of a celebrated career that has taken place almost entirely behind the political curtain, Nancy-Ann DeParle was introduced to a microphone on Monday by the President of the United States on live television, and she almost turned it down. "Nancy, do you want to say a little something?" Obama asked her at the end of a ceremony in the East Room. "Go ahead."

She shook her head a couple times in response, apparently saying no. But almost instantly she appeared to realize that this answer would not do, not on national television and not to the President. So DeParle quickly accepted the inevitability of her situation, turning to the cameras without any notes and rapidly thanking Obama for appointing her as the nation's director of the White House Office of Health Reform, a job that will put her at the center of this year's effort to overhaul both the cost and the availability of medical care in America. "I'll just say that I'm really honored," she began, speaking swiftly. (See who's who in Obama's White House.)

The good news for DeParle is that her new job won't require much public salesmanship. The White House already has a handful of health-care reformers who spend a lot of time talking to the American people, from the President himself to Peter Orszag, the budget director, to Kathleen Sebelius, the newly nominated Secretary of Health and Human Services (HHS). Sebelius, the popular Kansas governor, was introduced alongside DeParle on Monday. DeParle, by contrast, is being tasked with what she has always done best, working behind the scenes to improve the health-care system. (See the top 10 medical breakthroughs of 2008.)

Her résumé is the kind that Presidents love to promote: Harvard Law, Rhodes Scholar, named in 1994 by TIME as one of "America's 50 Most Promising Leaders Under 40." She ran health services in her home state of Tennessee, worked in the Clinton White House on health policy in the early 1990s and oversaw the Medicare and Medicaid programs at that decade's end. Since then she has become a highly sought-after corporate, academic and foundation consultant, earning enough money with her husband, New York Times reporter Jason DeParle, to buy a $3 million house in the Washington suburbs in 2007.

More important, DeParle is universally known in health-care-policy circles as one of the brightest minds of her generation. Obama now hopes that she is one of a select group who knows enough to make health reform happen this year. Her position, which is informally called White House health czar, was originally created as an add-on title for former Senate majority leader Tom Daschle, who had to withdraw from consideration for Health and Human Services Secretary because of tax problems. But with Daschle out, the White House decided that it still needed a high-level coordinator for the reform effort. "It's good to have someone who is really riding herd and only thinking of one thing," said one White House official.

As it stands, there are lots of cooks in the health-care-reform kitchen. But none of them is exclusively focused on that crucial, demanding effort. Sebelius has a bipartisan reputation and a background as her state's insurance commissioner, but at HHS she will oversee a massive organization with 10 operating divisions. Orszag must focus on the entire government budget. The head of the National Economic Council, Larry Summers, who has taken a particular interest in health care, has a portfolio that ranges from bank bailouts to global financial regulation. The other legislative, political and managerial staff at the White House spend their days stretched over dozens of subject areas. In this chaotic situation, DeParle will be charged with never letting health care get off track. (Read "Who Will Push Health-Care Reform in Place of Daschle?")

Although the responsibility is new for DeParle, the area of expertise is not. Back in 1993, when Hillary Clinton mounted an effort to reform health care, DeParle was at the Office of Management and Budget working on health-expenditure budget-crunching and statistical analysis. Her interest in managing and reforming Medicare and Medicaid has never really abated. "I don't know if you would say this is her second bite at the apple or if you would say this is a long-standing meal," jokes Chris Jennings, who served as Bill Clinton's chief health adviser.

DeParle comes to the job with a wide range of private-sector connections, some of which could prove problematic. For years she worked as a health-care adviser at JPMorgan Partners, a private equity firm, and CCMP Capital Advisers, another private investment firm with significant health-care holdings. She has served as a director on companies as varied as Cerner, which develops electronic medical records, and DaVita, which provides dialysis service. The companies and their investments could well be effected by the direction of health reform, which will necessarily seek to reduce costs in some areas, while increasing investments in others. (See the most common hospital mishaps.)

Under the ethics rules that Obama adopted in January, political appointees cannot "participate in any particular matter involving specific parties that is directly and substantially related to a former employer" for two years. A second White House official said on Monday that this rule would not prevent DeParle from doing her job. "She will recuse herself from what she needs to," the official said. "She does not need a waiver."

The bigger question is how well she will be able to work with lawmakers, who are already well on their way developing plans to extend coverage and reduce health-care costs. But that job, like that of managing the internal White House deliberations, will place DeParle squarely in her comfort zone, not in front of television cameras but in backrooms wrestling with the extraordinarily complex details of remaking a broken health-delivery system. "We're going to get to work," announced Obama as soon as DeParle had finished her brief remarks on Monday. And then the new health czar walked away from the podium, through ornamented White House doors and out of the public eye.