Washington ? The last thing the Bush White House and the rest of the country needed in these economically trying times was another financial crisis. But they got one.

The Republican administration and Democratic-run Congress now are facing the possibility that mortgage giants Fannie Mae and Freddie Mac, once staid and stable, could need a bailout or even go under.

Their default would send shock waves through already distressed financial markets, drive the U.S. economy further into recession territory and make it even harder for people to obtain mortgages or refinance their homes.

If their financial health continues to deteriorate, the government may have little choice but to take them over, bail them out or do both.

A Federal Reserve spokeswoman said the central bank had not talked with Fannie and Freddie about any emergency lending program. She declined to discuss any other options being considered.

The two government-chartered, shareholder-owned companies own or guarantee more than $5 trillion of home loans, roughly half of all outstanding U.S. mortgage debt.

Their role has become even more crucial as home prices keep falling and mortgage defaults keep rising.

The two companies’ stocks are now at their lowest levels in 16 years, down 80 percent from just a year ago.

The companies buy mortgages, turn them into securities and sell them to investors. They also hold some mortgages in their own portfolios. Because they were sponsored by the government and deemed to be nearly risk-free, they have been able to borrow money at slightly below-market rates.

While most of the mortgages they hold are fixed-rate loans to borrowers with good credit, the housing downturn has been so severe that they have sustained gigantic losses in their loan portfolios from foreclosures – about $11 billion over the past few months.

Mark Zandi, chief economist at Moody’s Economy.com, said he doesn’t think the two mortgage companies are yet at the point of default. “Yet, the pessimism is so dark, it can become self-fulfilling.”

Elsewhere Friday, federal regulators were forced to seize California-based IndyMac Bancorp after a run by depositors led to the second-largest failure ever of a U.S. financial institution. The bank, which was taken over the Federal Deposit Insurance Corp., became the first major bank to shutter its doors since the savings and loan crisis of the early 1990s.