For over a year now, Marilyn Tavenner has run the federal government's largest agency: the Centers for Medicare and Medicaid Services. With a budget of nearly $1 trillion, Tavenner oversees everything from the implementation of the Affordable Care Act to programs that already administer health benefits to more than 80 million Americans. The White House nominated Tavenner for the post in November 2011, but with the fight over the Affordable Care Act still winding its way up to the Supreme Court, she never received a confirmation hearing. She was then renominated in January, and a hearing now looks likely. In her first interview since her renomination, Tavenner and I spoke about the work she's done over the past year.