WASHINGTON — The nation's hospitals will give up $155 billion in future Medicare and Medicaid payments to help defray the cost of President Barack Obama's health care plan, a concession the White House hopes will boost an overhaul effort that has hit a roadblock in Congress.

Vice President Joe Biden announced the deal today at the White House.

"Reform is coming," he said. "It is on track. ... We have never been as close as we are today."

Obama hopes to sign a comprehensive bill in October.

However, the deal with the hospitals also might be on shaky ground. Officials said it is pegged to the Senate Finance Committee legislation, and whose prospects are uncertain. It would follow concessions from drug companies, and an announcement by Wal-Mart last week that it would support an employer requirement to help pay for health care.

Of the $155 billion in projected savings from hospitals, about $40 billion to $50 billion would come from reducing federal payments hospitals receive for providing care to uninsured and low-income patients, according to lobbyists. Those payments are now made through the Medicare and Medicaid programs.

The Medicaid cuts would be apportioned by state, as 10 percent annual reductions beginning around 2015.

About $100 billion more would come from reductions in Medicare payments to hospitals. A small amount of savings would come from trimming the money hospitals get for preventing patients from being readmitted for additional care.

Hospitals also would get something out of the deal. They won an agreement that if the Finance Committee's legislation includes a public health insurance plan, it would reimburse hospitals at above the rates Medicare and Medicaid pay, which hospitals have long complained are insufficient.