By Ferdous Al-Faruque - 06/09/14 10:01 AM EDT
Kathleen Sebelius handed leadership of the Health and Human Services Department to her successor on Monday and wished new Secretary Sylvia Matthews Burwell the best of luck.
Sebelius, who oversaw the passage and implementation of ObamaCare at the agency, is concluding an up-and-down tenure.
She also expressed her gratitude to the HHS staff.
“It has been my honor to serve - I'll always be grateful for this opportunity. Working with you during this historic time has been amazing!” tweeted Sebelius.
Sebelius announced her decision to step down in April, days after the administration announced 8.1 million people had enrolled in ObamaCare.
That followed months of worries for the administration that enrollment would come in weaker than expected because of problems with the HealthCare.Gov web site.
Burwell went through a very quick and relatively painless nomination hearing to replace Sebelius. Last week she was appointed by the Senate in a 78-17 vote with 20 Republicans crossing the aisle to support her.
HHS also thanked Sebelius for her "service and commitment" through its official Twitter account and later in the day welcomed Burwell with a photo of her shaking hands with HHS employees.
Welcome Secretary Sylvia Mathews Burwell! pic.twitter.com/oCUSSdmf6S— HHS.gov (@HHSGov) June 9, 2014
— This article was updated at 12:00 pm EST.