WASHINGTON — The Federal Reserve today introduced a new program to finance the purchases of assets from money market mutual funds as the government continued to search for ways to battle a severe credit crisis.

"The short-term debt markets have been under considerable strain in recent weeks as money market mutual funds and other investors have had difficulty selling assets to satisfy redemption requests," the Fed said in an announcement of its new effort.

JPMorgan Chase & Co. was chosen to run five special funds that will buy certificates of deposit, bank notes and commercial paper from money market mutual funds. The Fed will lend up to $540 billion to the five funds to support the effort.

Fed officials said that about $500 billion had flowed out of prime money-market funds since August as investors began to worry about their ability to redeem their investments. On Sept. 18, the Treasury Department announced it was tapping a $50 billion Treasury fund to provide guarantees for the assets in the funds. The new Fed initiative is designed to bolster the funds further.

Meanwhile, the Treasury Department announced today that it had selected two major accounting firms to help manage the government's $700 billion rescue program for the financial system.

The department selected Pricewaterhouse Coopers to be an auditor for the program that will purchase troubled assets from financial institutions while Ernst & Young was chose to provide general accounting support.

Those announcements came as the House Financial Services Committee held a hearing today in which experts discussed what needs to be done to improve the government's regulatory structure. The aim is to find a way to better manage the financial system to prevent another financial crisis.

Democrats in Congress were also pushing ahead with efforts to assemble a second economic stimulus program. That effort got a timely endorsement on Monday from Federal Reserve Chairman Ben Bernanke.

Wall Street pulled back today as investors decided to cash in some of the big gains of the previous session. The Dow Jones industrial average was down 245 points in early afternoon trading, a retreat following a gain of 413 points on Monday.

The credit markets made more moves to mount a recovery following the severe disruptions that began in mid-September with the bankruptcy filing of Lehman Brothers Holdings Inc. Rates on loans between banks and yields on Treasury bills returned to their levels of late September.

The White House said Monday that President Bush was at least willing to consider a second stimulus measure to follow a $168 billion program passed in February and a $700 billion financial system rescue plan passed on Oct. 3.

Democrats say any stimulus bill would include items previously rejected by Bush such as road and bridge construction money and help for state budgets. Another round of tax rebates is possible, too, to make the measure big enough to jolt the economy, which many economists think has already slipped into recession.

Sen. Charles Schumer, D-N.Y., predicted Congress would return after Election Day to work on a measure equal to or exceeding February's $168 billion stimulus package, which included $600 tax rebates for most individuals and tax breaks for businesses.

Despite the new momentum, action in November is by no means certain. There's a narrow window between the elections and Thanksgiving, and the results of the elections are likely to affect both sides' willingness to bargain.

Democrats hope Bernanke's endorsement will help bring Bush around, and they predicted that congressional Republicans would warm to the idea as well. Bush has been strictly opposed to Democratic proposals such as infrastructure projects.

"We're continuing to have conversations with members of Congress, and we're open to ideas that they would put forward ... that would stimulate the economy and help us pull out of this downturn faster," White House press secretary Dana Perino said Monday, shortly after Bernanke endorsed the need for a fresh and "significant" round of government action.

"What we've seen put forward so far by the leaders in Congress, the Democrats, were elements of a package that we did not think would actually stimulate the economy," Perino added.

House Speaker Nancy Pelosi of California and fellow congressional Democrats are pushing a package that could cost as much as $150 billion or more.

As part of that package, Pelosi wants to resurrect a $61 billion House-passed measure that included about $37 billion in public works spending, $6 billion to extend jobless benefits, $15 billion to help states pay their Medicaid bills and $3 billion in food stamp assistance for the poor.

Democrats also are considering a second round of tax rebates to follow the $600-$1,200 checks most individuals and couples got earlier this year. That money, going directly to consumers in hopes they would spend it, could push the price tag much higher.

As the value of their homes, pension funds and other investments has dropped in the past year, consumers have become more reluctant to spend. Consumer spending makes up more than two-thirds of the economy. When spending declines, it forces businesses to either stop hiring or cut jobs.

Unemployment now stands at 6.1 percent. Economists predict it could go as high as 7.5 percent in 2009.