President Barack Obama on Friday named a Washington veteran with a bipartisan track record in the White House to a top economic post, the latest move in a shake-up of Obama's staff following Republican gains in congressional elections.

Gene Sperling's appointment as director of the National Economic Council coincided with the release of the December jobs report that showed the unemployment rate dropping to 9.4 percent, its lowest level in nearly two years.

But job growth fell short of expectations, and Obama said that Sperling, along with other newly appointed members of the economic team, have a challenging task ahead.

"Our mission has to be to accelerate hiring and accelerate growth," Obama said during remarks at a window manufacturing plant in suburban Maryland. "That depends on making our economy more competitive."

The head of the U.S. central bank, Federal Reserve chairman Ben Bernanke, also sketched a more optimistic outlook for the U.S. economy on Friday, but cautioned that it would take time for the job market to improve.

Sperling, a counselor to Treasury Secretary Timothy Geithner, is returning to a familiar role. He served as NEC director in Bill Clinton's administration, where he played a key role in the 1993 deficit reduction bill and compromised with a Republican-led Congress on the 1997 balanced budget agreement.

The role gives Sperling broad oversight of the administration's economic policies as the White House contends with near-double digit unemployment and looming legislative battles on the budget and deficit now that Republicans have taken control of the House of Representatives and cut into Democrats' majority in Senate.

Sperling takes over the council post from Lawrence Summers, who left the White House last month to return to Harvard University.