Although the details of the F.D.I.C. part were still being completed on Friday, it is expected that the government will provide the overwhelming bulk of the money — possibly more than 95 percent — through loans or direct investments of taxpayer money.

The hope is that such a generous taxpayer subsidy will attract private investors into the market and accelerate the recovery of the country’s banks.

The key protection for taxpayers, according to people briefed on the plan, is that the private investors will bid in auctions against each other for the assets. As a result, administration officials contend, the government will be buying the troubled loans of the banks at a deep discount to their original face value. Because the government can hold those mortgages as long as it wants, officials are betting the government will be repaid and that taxpayers may even earn a profit if the market value of the loans climbs in the years to come.

To entice private investors like hedge funds and private equity firms to take part, the F.D.I.C. will provide nonrecourse loans — that is, loans that are secured only by the value of the mortgage assets being bought — worth up to 85 percent of the value of a portfolio of troubled assets.