WASHINGTON — In a renewed bid to stave off foreclosures, the Obama administration will propose measures today to give some jobless homeowners a three-month break on payments and give lenders more incentives to reduce the principal on delinquent loans.

The new measures come on top of a series of steps administration officials announced yesterday to fortify their $75 billion effort to modify mortgages and reduce foreclosures. To date, those efforts have focused on giving lenders cash incentives to ease payments by extending the payout period for loans.

The initiative to give jobless homeowners a reprieve on payments and to entice lenders to cut the principal was disclosed to a knowledgeable industry official, who did not want to be quoted publicly in advance of the plan's unveiling.

"These program adjustments will better assist responsible homeowners who have been affected by the economic crisis through no fault of their own," an Obama administration official said. "The program modifications will expand flexibility for mortgage servicers and originators to assist more unemployed homeowners and to help more people who owe more on their mortgage than their home is worth because their local markets saw large declines in home values."

The new steps by the administration amount to an acknowledgment the year-old program hasn't done enough. By the end of December, it had permanently lowered monthly payments for about 170,000 borrowers out of the expected 3 million to 4 million it was aimed at covering through 2012.

Even so, the program and separate efforts by banks and other lenders to rework overdue loans have pushed the rate of new foreclosures down 15.4 percent in the final three months last year, according to a federal report released yesterday.

But the report also sounded alarms about a potential looming tide of foreclosures. The number of borrowers who were 90 days or more past due on their mortgage payments, a key measure of future defaults, swelled 20.4 percent in the last quarter over the previous quarter.

Worse, about 52 percent of those with modified loans defaulted again after nine months, said the report from the Office of the Comptroller of the Currency and the Office of Thrift Supervision, which cover about two-thirds of the outstanding home loans.

The time bomb of delinquencies and repeat defaults has focused more attention on the administration's Home Affordable Mortgage Program, which President Obama launched with great fanfare more than a year ago.

At a House hearing yesterday, frustrated lawmakers labeled the program a bust so far, echoing a stinging report this week by a government watchdog.

"This program is a failure and a waste of taxpayer dollars," said Rep. Patrick McHenry, R-N.C.

Assistant Treasury Secretary Herbert M. Allison admitted that modifying mortgages has been more difficult than administration officials had anticipated.

"Certainly we've seen a lot of frustration with this program since its inception," he told lawmakers. "We did not fully envision the challenges we would encounter."

Among the changes to take effect June 1 is a prohibition on mortgage servicers from starting or continuing foreclosure proceedings on a borrower who enters the Home Affordable Modification Program. Companies servicing mortgages also must screen every borrower who has missed two or more payments to determine whether the borrower is eligible for the program.

In addition, Allison said, the administration was preparing to move forward with an initiative to modify second mortgages after four of the largest mortgage servicers — Bank of America Corp., Citigroup Inc., JPMorgan Chase & Co. and Wells Fargo & Co. — agreed to participate.