Sebelius said she also was determined to correct some of the "misinformation and confusion about what happens and when it happens," Politico reported Friday.
In an interview with the Washington publication, the secretary pledged a hands-on approach, "a sense of urgency and as much say-so for the states as possible."
The department's payroll of nearly 80,000 employees likely would grow, but by how much hasn't been determined, Sebelius said.
"Some of what is anticipated is new responsibilities, potentially -- not necessarily new people or new bureaucracies," she said. "I'm a big believer that you start with assuming that you do more with less. ... We have new responsibilities, but we've got to figure out what, within our resources, we have the capacity to take on immediately."
She said she would be working to ensure "the promise of this historic legislation is really delivered a step at a time and in a very confident way."
Sebelius told Politico administration lawyers assured her the healthcare bill is on "strong" legal ground, so she said she would let lawyers worry about constitutional challenges by 14 state attorneys general.