Barring any problems uncovered in a background investigation under way by Senate staff, Burwell, the current director of the Office of Management and Budget, is likely to succeed Kathleen Sebelius as the next leader of the Department of Health and Human Services. She'll also take over as chief administrator of the Patient Protection and Affordable Care Act, the $1.4 trillion expansion of health insurance.

Burwell provided a vigorous defense of Obamacare at a congressional hearing today where the law took center stage, saying that it had reduced federal health spending and improved the lives of millions of Americans. Republican allies, while parting with her on the issue, said she was highly qualified to lead the health department.

"Ms. Burwell has the qualifications to run HHS and has me assured that she will work with members of Congress, as she has as director of OMB, and be more responsive to its members than her predecessor," Senator John McCain, an Arizona Republican, said at the hearing while introducing her. He joked that he had advised her not to take the job.