DAVOS, Switzerland  Over the years, the United States has fulfilled many roles at the World Economic Forum: dot-com dynamo, benevolent superpower, feared aggressor. Now add wounded giant.

On the first day of the annual conference here, a parade of bankers, economists and government officials expressed deep fears about the faltering American economy  and blunt criticism, particularly of the Federal Reserve, which some blame for sowing the seeds of today’s crisis.

For George Soros, the financier who made a fortune betting against the British pound, the slump now goes beyond subprime loans. It signals a reordering of the postwar economy and the end of dollar dominance.

“The current crisis is not only the bust that follows the housing boom,” Mr. Soros declared. “It’s basically the end of a 60-year period of continuing credit expansion based on the dollar as the reserve currency.”