SAN FRANCISCO -- In just two weeks the estimated losses in retirement accounts like 401ks due to the economic downturn have now doubled to $4 trillion, East Bay Congressman George Miller revealed on Wednesday.

Miller, D-Martinez, was in San Francisco Wednesday to hold hearings of the House Committee On Education and Labor he chairs, when he made the comments sounding a further alarm for aging baby boomers.

Two weeks ago, Peter Orszag, the head of the Congressional Budget Office, told the Miller’s committee meeting in Washington, D.C., that Americans' retirement plans had lost as much as $2 trillion in the past 15 months - about 20 percent of their value.

As Congress investigates the causes and effects of the meltdown, Miller’s committee has been pressing economists and other analysts on how the housing, credit and other financial troubles have battered pensions and other retirement funds, which are among the most common forms of savings in the United States.

"Unlike Wall Street executives, America's families don't have a golden parachute to fall back on," Mille said at the earlier hearing. "It's clear that their retirement security may be one of the greatest casualties of this financial crisis."

More than half the people surveyed in an Associated Press-GfK poll taken Sept. 27-30 said they worry they will have to work longer because the value of their retirement savings has declined.

Orszag indicated the fear is well founded. Public and private pension funds and employees' private retirement savings accounts - like 401(k)s - lost about 10 percent between the middle of 2007 and the middle of this year, and lost another 10 percent just in the past three months, he estimated.

Private retirement plans may have suffered slightly more because those holdings are more heavily skewed toward stocks, Orszag added.

"Some people will delay their retirement. In particular, those on the verge of retirement may decide they can no longer afford to retire and will continue working," Orszag said.

A new AARP study found that because of the economic downturn, 1 in 5 workers 45 and older has stopped putting money into a 401(k), IRA or other retirement savings account during the past year, and nearly 1 in 4 has increased the number of hours he works. More than one-third of these workers have considered delaying retirement, according to the study, which also found that more than half now find it difficult to pay for basic items such as food, gas and medicine.

Even before the recent downturn, older Americans were on track to continue working longer. Twenty-nine percent of people in their late 60s were working in 2006, up from 18 percent in 1985, according to the Bureau of Labor Statistics. Over the next decade, the number of workers who are 55 and older is expected to increase at more than five times the rate of the overall workforce, the BLS reported.

Falling home values and now the decimation of much of their savings could plunge older Americans into a period of austerity not seen in decades, Miller said: "The fear factor is huge, and they don't see the availability of resources to them to get well."