With lawmakers worried that older Americans relying on Medicare could begin losing access to health care, the Senate on Friday approved a six-month plan to prevent a steep cut in doctor fees paid by the federal health program.

The $6.4 billion measure would reverse a 21 percent cut in physician payments that was to kick in Friday, raising the possibility that some doctors might begin to turn away those covered by Medicare. The legislation, known on Capitol Hill as the ‘doc fix’, was approved without a roll call vote after leaders of both parties agreed to pull it out of a stalled package of tax changes and safety-net spending.

Senator Max Baucus, the Montana Democrat who is chairman of the Senate Finance Committee, said the legislation was needed to avert “near chaos in absence of medical care to seniors.”

The cost of the measure was offset by changes in Medicare billing regulations, antifraud provisions and tightening some pension rules, eliminating Republican objections that it would put the federal government deeper into the red.

“We’ve done it without adding to the deficit, and I think that is something both sides can feel good about,” Senator Mitch McConnell of Kentucky, the Republican leader, said.

The measure must still be approved by the House, which returns next week.

Though the Senate made progress on the Medicare front, it faces difficulty in resolving other stalled issues, including $40 billion in added unemployment benefits and $24 billion in aid to states to provide health care to the poor. Democrats failed to break a partisan stalemate over those programs on Thursday night.