Image of male nurse pushing senior woman in a wheelchair in nursing facility

The nation’s top Medicare official, Jonathan Blum, is leaving his post next month, news outlets reported Tuesday. Blum became a familiar figure to long-term care providers through Open Door Forum calls and other outreach efforts during his five-year tenure, as he guided implementation of Medicare reforms under the Affordable Care Act.

Under his watch, Medicare began a dramatic shift away from fee-for-service and toward Accountable Care Organizations, bundled payments and other payment schemes meant to coordinate care across the acute and post-acute continuum. In an internal email announcing Blum’s departure, Centers for Medicare & Medicaid Services Administrator Marilyn Tavenner praised his efforts on this front and said his accomplishments are “too many to list,” according to Reuters.

Blum’s official title is Medicare Director and Principal Deputy Administrator of the CMS. His last day will be May 16, and Tavenner said only that he is departing to pursue new opportunities, Reuters reported. Two of the most recent Medicare changes — cutting reimbursements to Medicare Advantage physicians and changes to Part D — encountered stiff resistance and were largely scrapped.

The Department of Health & Human Services — of which CMS is a part — already is in flux, as HHS Secretary Kathleen Sebelius announced her resignation earlier this month. President Barack Obama nominated Sylvia Mathews Burwell, head of the White House Office of Management and Budget (OMB), to replace her. Blum also served a stint in the OMB, and has been a vice president overseeing Medicaid and Long-Term Care at Avalere Health.

The White House has not yet floated a replacement for Blum, who was Obama’s first appointment to CMS.