Barack Obama's Health and Human Services Secretary Kathleen Sebelius is to resign, paying the price for the chaotic initial rollout of the US president's signature health care law, officials say.
Ms Sebelius will officially step down on Friday and Mr Obama will nominate Sylvia Mathews Burwell, his current budget director, to replace her, the officials said on Thursday.
The administration will hope that her departure will draw a symbolic line under the early implementation period of the law, which had a botched debut due to a malfunctioning sign-up website, AFP reports.
The administration was forced into an emergency effort to fix the site and other implementation problems - and 7.5 million people have now signed up for health insurance under the new law.
Mr Obama and top aides spent last week declaring victory over skeptics who argued that the law would never work or that Americans would refuse to sign up.
But the stuttering start to so-called 'Obamacare' provided fresh ammunition to Republicans who are using the law's unpopularity to blast vulnerable Democrats ahead mid-term elections in November.
Republicans see Obamacare as inappropriate government intrusion into the healthcare industry. US residents face a tax penalty next year if they do not have some form of health coverage, the BBC reports.
The 2010 law is intended to extend health insurance to the roughly 48 million Americans who do not receive it through their employers, the government, or a privately purchased plan. It also aims to slow the growth in the cost of healthcare and requires private plans to meet a certain level of coverage.
Kathleen Sebelius has been health secretary since Mr Obama took office in 2009 and made the decision to resign herself, the New York Times reported. Ms Burwell is known in the White House for quiet competency and Mr Obama will look to her to smooth out teething problems with Obamacare before the next registration period opens in November.