Health and Human Services Secretary Kathleen Sebelius was the icy and determined face of Obamacare from the beginning.
But she was always President Barack Obama's second choice for the job, and before she resigned on Thursday after overseeing the rocky rollout of his signature health reform law, he snubbed her.
When he announced enrollment on the exchanges had surpassed 7 million — far more than anyone expected when the exchanges failed badly for the first two months, it was Vice President Joe Biden, not Sebelius, who stood victoriously at his side.
Sebelius, who was regularly hauled before Congress to defend the law's rollout, was never allowed, or perhaps chose never to step forward, to announce any of the law's successes.
Sebelius will be replaced by Sylvia Mathews Burwell, currently director of the White House Office of Management and Budget, U.S. officials told NBC News.
"Secretary Sebelius notified the President in early March of her decision," a White House official said in a statement.
"At that time, Secretary Sebelius told the President that she felt confident in the trajectory for enrollment and implementation of the Affordable Care Act, and that she believed that once open enrollment ended it would be the right time to transition the Department to new leadership."
Sebelius hung tough through the entire battle first to get the law written and passed, and then through challenges that went all the way to the Supreme Court. The administration had to push the law through Congress without a single Republican vote, setting it up for a vicious battle that made every step of its implementation a nail-biter.
Even as HHS officials worked nights and weekends to get the final rules into place, the administration was fighting opponents who threw up legal arguments that brought the law's constitutionality into question. And when the Supreme Court finally upheld the law on the last day possible of June 2012, it left Sebelius's HHS just a few months to put its crowning glory — the health insurance exchanges — into operation.
Sebelius, a former governor of Kansas and before that the state's insurance commissioner, was the face of the project. And behind the scenes, she was popular with insurance companies whose cooperation was vital for the law's success. They felt she understood their needs.
But members of Congress howled for her resignation after the online website HealthCare.gov fell apart on its debut and as revelations of mismanagement emerged at hearing after hearing. Sebelius held firm and Obama expressed confidence in her leadership.
Sebelius, 65, was nominated as HHS Secretary in February 2009 after a scandal over taxes forced former senator Tom Daschle, Obama's first choice, to step aside.