FOR FIVE YEARS, US Health and Human Services Secretary Kathleen Sebelius has been a lightning rod for critics of President Barack Obama’s health care law.

But with sign-ups exceeding expectations and a new face soon to be in charge at HHS, the White House is eager to see if the poisonous atmosphere might give way to more pragmatic efforts aimed at fixing problems with America’s newest social program.

Obama will announce Sebelius’ resignation today and nominate his budget director, Sylvia Mathews Burwell, as her replacement. The moves come just over a week after sign-ups closed for the first year of insurance coverage under the so-called Obamacare law.

The opening weeks of the enrolment period were marred by website woes, straining ties between Sebelius and officials in the West Wing.

Though the administration rebounded strongly and exceeded expectations by enrolling 7.1 million people by the March 31 deadline, the comeback wasn’t enough to tamp down Republican criticism of Sebelius or boost the public’s perception of the federal health care overhaul.

Enrolment has since risen to 7.5 million as people were given extra time to complete applications.

Even with the robust enrolment, huge implementation challenges remain. The administration has to improve customer service for millions of Americans trying to navigate the new system.

Sebelius’ relationship with the White House frayed during the fall roll-out of the insurance exchanges that are at the centre of the sweeping overhaul. The president and his top advisers appeared caught off guard by the extent of the website problems, with warnings from those working on the technology never making it to the West Wing.

Sebelius took personal responsibility for the chaotic launch of the website and asked the HHS inspector general to conduct an investigation. That report is not expected for months.

Read: Late surge in enrollment for Obamacare as deadline hits