Back on duty at the White House after a week-long trip, President Obama used the announcement of his pick for surgeon general to send a message on health care reform, warning his critics: "Don't bet against us."

The president praised the work of House and Senate committees thus far, and said he has no illusions about the challenge of getting a final bill over the finish line. But the cost of inaction is too high, he said, calling the current system "unsustainable."

"I understand that people are a little nervous and a little scared about making change," he said during the Rose Garden announcement. "The muscles in this town to bring about big changes are a little atrophied. But we're whipping folks back into shape. We are going to get this done."

Dr. Regina Benjamin, an Alabama family doctor, is Obama's choice for surgeon general, a long-delayed nomination for the nation's top doctor. He said Benjamin, because of her background, understand the need for reform "in a powerful and personal way." Benjamin called the selection "a physician's dream."