WASHINGTON — President Barack Obama's top economic adviser said this morning the nation's economic crisis has led to an "excess of fear" among Americans that must be broken to reverse the downturn.

"Fear begets fear," and that "is the paradox at the heart of the financial crisis," Lawrence Summers, the president's director of the National Economic Council, told a forum.

"It is this transition from an excess of greed to an excess of fear that President Roosevelt had in mind when he famously observed that the only thing we had to fear was fear itself," Summers said. "It is this transition that has happened in the United States today."

Summers spoke amid new signs of a deepening recession. The U.S. trade deficit plunged in January to the lowest level in six years as the economic downturn cut America's demand for imported goods, the Commerce Department reported today.

The economic adviser said it is still too early to gauge the broad impact of the president's recovery program.

"But it is modestly encouraging that since it began to take shape, consumer spending in the U.S., which was collapsing during the holiday season, appears, according to a number of indicators, to have stabilized," Summers told the Brookings Institution, a think tank.

Summers was asked by a member of the audience what the nation's business community could do to help speed the recovery.

"What we need today is more optimism and more confidence," Summers said.