WASHINGTON — President Barack Obama made it official this morning: Health and Human Secretary Kathleen Sebelius is out and budget chief Sylvia Mathews Burwell is in.

Obama praised Sebelius for helping to steer his health care law’s comeback after a rocky rollout, even as he nominated a successor aimed at helping the White House move past the political damage.

“Under Kathleen’s leadership, her team at HHS turned the corner, got it fixed, got the job done,” Obama said in a Rose Garden ceremony this morning. “And the final score speaks for itself.”

About 7.5 million people have enrolled in the health law, exceeding expectations after website woes stymied sign-ups for weeks.

Obama nominated Burwell to replace Sebelius, calling her “a proven manager” who knows how to get results.

The nomination of Burwell, who was unanimously confirmed by the Senate for her current post last year, appeared aimed at avoiding an election-year confirmation fight.

“Last time, she was confirmed unanimously,” Obama said. “I’m assuming not much has changed since that time.”