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U.S. health official Michelle Snyder, who oversaw the building of the troubled Obamacare website, HealthCare.gov, is retiring from her job as chief operating officer at the Centers for Medicare and Medicaid Services (CMS).

CMS chief Marilyn Tavenner announced Snyder's departure to senior staff last week in a statement viewed by Reuters on Monday. The statement said Snyder had originally planned to retire at the end of 2012, but stayed on at Tavenner's request to, "help me with the challenges facing CMS in 2013."

CMS is the agency responsible for implementing much of the new healthcare law, including the construction of the federal website, HealthCare.gov, that allows consumers in 36 states to buy insurance through an online marketplace. Fourteen states and the District of Columbia run their own online exchanges.

HealthCare.gov crashed soon after its launch on October 1, as millions of visitors entered the site, and remained balky for much of the ensuing weeks. The disastrous rollout disappointed those who hoped to use the site to enroll in subsidized health insurance, and damaged the credibility of the president and his signature domestic policy achievement.

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In this Nov. 5, 2013, photo, Medicare chief Marilyn Tavenner testifies on Capitol Hill in Washington. Tavenner announced the departure of Michelle Snyder, who oversaw the building of the troubled Obamacare website. J. Scott Applewhite / AP

Snyder, a career bureaucrat, was identified by U.S. Health and Human Services Secretary Kathleen Sebelius at a hearing in October as the CMS official who decided to have the federal government fulfill the key role of system integrator for HealthCare.gov.

But Sebelius also told lawmakers: "Michelle Snyder is not responsible for the debacle. Hold me accountable for the debacle. I'm responsible."

Sebelius is still in her job.

Snyder has not taken a public role in defending the administration's work on HealthCare.gov or its efforts to fix the website.

Since the botched rollout turned into a major political debacle, CMS underwent a management shuffle, but it did not include high-profile departures. However, in early November, CMS quietly announced that its head of technology, Tony Trenkle, was leaving for the private sector.

Tavenner praised Snyder's "intelligence, experience and formidable work ethic" in her email announcing Snyder's departure, which did not explicitly mention the HealthCare.gov website.

In a December 1 report, Jeffrey Zients, the crisis manager brought in to salvage the website and make it operate smoothly for most visitors, blamed the crisis on poor management, slow decision-making and a lack of accountability among those responsible for HealthCare.gov.

While the consumer-facing part of the website has improved, Snyder's departure comes as officials race to finish critical "back end" features. Missing pieces include software that will enable the federal government to verify enrollment data with issuers and to pay plans billions of dollars in federal subsidies on behalf of lower income enrollees.

The Obama administration announced on December 17 that former Microsoft Corp executive Kurt DelBene will oversee the revamped HealthCare.gov website and expand on technology improvements achieved by Zients.