The Obama administration’s implementation of the 2010 healthcare law will help shape the president’s legacy, for better or worse.

{mosads}Federal and state officials are preparing to launch the health law’s insurance exchanges on Oct.1. But while most attention is trained on federal Health secretary Kathleen Sebelius, there are many others behind the scenes playing important roles in setting up the health exchanges, preparing for the Medicaid expansion and trying to get the public on board.

The Affordable Care Act (ACA) has been called one of the most complex government undertakings in a generation. It will touch almost every corner of the U.S. healthcare system and define that arena for the foreseeable future.

Here are 10 key players to watch as the law is implemented.

* Debbie Curtis (Deputy Policy Director, District of Columbia Health Benefit Exchange)

Curtis is well known to many on Capitol Hill for her work on House Ways and Means Democratic staff and as chief-of-staff to former Rep. Pete Stark (D-Calif.), once the chairman of the powerful Ways and Means Health subcommittee. Curtis also lobbied for Consumer Action, a consumer advocacy group, during debate over the Clinton health plan.

As an expert on health insurance, Curtis was recruited early this year to help the District of Columbia set up its new health insurance marketplace. The exchange is notable because it’s where D.C.-based congressional aides will be required to purchase coverage. The District’s small businesses will also be required to purchase their employee health insurance through the marketplace starting in 2015 — an ongoing source of controversy in the city.

* Andy Allison (Arkansas Medicaid Director)

Allison has been called a visionary for his role in a proposal to use funding from ObamaCare’s Medicaid expansion to finance the purchase of private coverage for low-income people on the state’s insurance exchange. The plan is seen as a possible red-state alternative to the expansion and has been approved both by federal health officials and the Arkansas state legislature. It’s also expected that the plan could lower premiums on the exchange and draw in new insurance carriers.

Allison moved the Arkansas Medicaid program away from fee-for-service payments and toward a model that rewards quality and efficiency. He formerly served as head of Medicaid in Kansas, and started his work in the field as a Medicaid analyst at the Office of Management and Budget.

* Anne Filipic (Enroll America President)

Filipic is the woman who must sell ObamaCare to the public. As the head of Enroll America, a nonprofit group with close ties to the Obama administration, Filipic will lead a multi-million dollar campaign urging people without insurance to sign up for the new exchanges. She’s a veteran of the Health and Human Services Department, the Obama campaign and the White House, mostly recently working as deputy director of the Office of Public Engagement.

Filipic has said her campaign experience will be vital to leading Enroll America. “What I envision first is a lot of data and analytics, using a lot of the microtargetting that has taken off in recent years,” she told the Washington Post in January. “There’s some potential to do what electoral campaigns do: Find people who wouldn’t be motivated to take action and inspire them in a way that they do.”

* Anton Gunn (Director of External Services, Health and Human Services Department)

Gunn is leading the Health department’s outreach to stakeholders as the Affordable Care Act is implemented. A former member of the South Carolina House of Representatives, Gunn is responsible for maintaining good relationships between the Obama administration and powerful healthcare interest groups, many of which have become restless as the law’s enactment sees challenges.

Gunn made news in January when he announced a major semantic change related to the law’s enactment — the administration would be using the term “marketplaces” instead of “exchanges” because it translates better into Spanish.

“We know that 12 million of the people eligible [for the law’s benefits] speak Spanish, and one million more speak a language other than English or Spanish. These are the people we need to reach,” he told an advocacy conference.

* Timothy Jost (Professor of Law, Washington and Lee University School of Law)

To healthcare policy experts, Jost needs no introduction. The veteran law professor has become a nationally recognized expert on the ACA in the three years since its passage. His blog posts for the journal Health Affairs are considered must-reads in Washington because of their clarity and up-to-the-minute analysis.

“The guy is just an astonishing resource,” said a pro-ACA activist in Washington, D.C. “His knowledge is encyclopedic.” Jost also serves as a consumer liaison to the National Association of Insurance Commissioners.

* Denis McDonough (White House Chief of Staff)

President Obama’s chief of staff might seem like an obvious choice for this list, but McDonough is taking involvement with the ACA to a new level. According to unnamed aides quoted by Time, the former deputy National Security Advisor spends at least two hours a day on the law’s implementation, highlighting the high stakes facing the White House over the next year. Senior communications aides like Tara McGuinness, who came to the White House from the Center for American Progress this spring, reportedly work on the issue nearly full-time.

* Peter Lee (Executive Director, California Health Benefit Exchange)

Lee was recruited in 2011 to run California’s insurance exchange, a marketplace that is crucial to fulfilling ObamaCare’s mission of providing healthcare to the uninsured. He has close ties to the Obama administration, formerly serving as Deputy Director for the Center for Medicare and Medicaid Services, and his active approach to running the exchange is expected to serve as a model for other blue-state officials. As many as 5 million people could sign up for Covered California, making it ObamaCare’s largest new insurance marketplace.

* Sandy Praeger (Kansas Insurance Commissioner)

Praeger leads the key health insurance committee at the National Association of Insurance Commissioners, giving her a front-row seat as states grapple with predictions of “rate shock” under ObamaCare. As part of her work, Praeger has been advising states on how to mitigate potential rate increases through taxpayer subsidies or tighter regulations.

A former Kansas state lawmaker, Praeger now serves as insurance commissioner, making her a successor to Sebelius. Kansas won’t run its own insurance exchange, but Praeger, a centrist Republican, has reportedly been working to make sure residents can get their questions about ObamaCare answered by local officials. She’s also been a critic of fellow Republican officials as they refuse to implement the law.

* Jon Kingsdale (Executive Director, Wakely Consulting Group)

Kingsdale played a major role in launching healthcare reform in Massachusetts — ObamaCare’s predecessor — as the founding executive director of the state’s insurance exchange. Now he’s leading Wakely Consulting Group, advising other states as they implement their marketplaces.

The firm has also provided widely cited actuarial analysis of the law, and Kingsdale’s been quoted recently about efforts to sell the law to consumers. As head of the Massachusetts Health Connector, he was part of a partnership with the Boston Red Sox to encourage enrollment in the marketplace.

* Teresa Miller (Acting Director, Insurance Programs Group, Center for Consumer Information and Insurance Oversight)

Oregon’s former top insurance regulator joined the Health and Human Services Department in 2011 to work with state governments on the new exchanges. As director of oversight at the Medicare-Medicaid Center for Consumer Information and Insurance Oversight, Miller will be enforcing ObamaCare’s market reforms in more than 10 states starting next year.

She’s also worked on the law’s medical-loss ratio, which mandates that insurance companies issue rebates to consumers when they don’t spend at least 80 percent of patient premiums on medical care.