Bernanke: economy faces 'numerous difficulties'

At the same time, Bernanke, testifying before the Senate Banking Committee, sounded another warning that rising prices for energy and food are elevating inflation risks. This problem looms even as officials try to cope with persistent strains in financial markets, rising joblessness and housing problems.

The situation, he said, poses "significant challenges" for Fed policymakers as they try to chart the best course for keeping the economy growing, while making sure inflation doesn't dangerously flare up. All the economy's problems--including slumping home values, which threaten to make people feel less wealthy and less inclined to spend in the months ahead--represent "significant downside risks" to economic growth.

Over the rest of this year, the economy will grow "appreciably below its trend rate" mostly because of continued weakness in housing markets, high energy prices and tight credit conditions, Bernanke said.

President Bush tried to strike an encouraging note: "The bottom line is this: We're going through a tough time." but "I believe we will come through this challenge stronger than ever before."

On Wall Street, the Dow Jones industrial average 92.65 to 10,962.54. It was the blue chips' lowest close since July 21, 2006.

Bernanke's testimony comes just two days after the Fed and the Treasury Department came to the rescue of mortgage giants Fannie Mae and Freddie Mac, offering to throw them a financial lifeline.

The Fed chief was later joined by Treasury Secretary Henry Paulson and Securities and Exchange Commission Chairman Chris Cox, who were summoned to detail the rescue plan.

The two companies hold or guarantee more than $5 trillion in mortgages--almost half of the nation's total. The Bush administration is asking Congress to temporarily increase lines of credit to Fannie and Freddie and to let the government buy their stock. The Fed has offered to let the companies draw emergency loans.

The pledges of aid have raised concerns about the government's role in such financial problems and the risk to taxpayers.