Senate Majority Leader Harry Reid of Nevada, left, and Sen. Charles Schumer, D-N.Y. listen to Dr. Stacey Lindau of Chicago, accompanied by her son Benjamin, 11, speak Thurdsay, Dec. 10, during a health care news conference on Capitol Hill in Washington.

Senate Democrats are considering changing a proposed expansion of Medicare to address complaints from doctors and hospitals and defray costs for consumers, officials said Thursday, two days after party leaders hailed it as part of a breakthrough for health care.

Under the plan, uninsured individuals ages 55 to 64 could purchase coverage under Medicare. The expansion is part of a compromise for dropping a full-blown national government-run insurance plan from the legislation that Democrats and the White House hope to push through the Senate by Christmas.

In this Nov. 20, 2009, photo, Sen. John Thune, R-S.D., lifts a copy of the Democratic health care reform bill during a news conference on Capitol Hill in Washington.

The American Hospital Association and American Medical Association have both criticized the proposed Medicare expansion since it was announced Tuesday night, saying the program pays health care providers less than private insurance companies, and warning against increasing the number of patients.

“We are trying to find a solution,” Sen. Max Baucus, D-Mont., chairman of the Senate Finance Committee, told reporters in the Capitol, saying that the groups had raised legitimate concerns.

Separately, officials said there were discussions about the possibility of defraying the expense of Medicare coverage for uninsured individuals under 65. Under some estimates, the cost could be as high as $7,600 annually — more than $600 a month — until subsidies become available in 2014.

Current Medicare beneficiaries pay $96.40 per month, with the government picking up the rest of the premium cost.

The officials spoke on condition of anonymity, saying they were not authorized to discuss possible changes publicly.

The other key part of Tuesday night’s compromise called for creation of private insurance plans to be overseen by the Office of Personnel Management, the federal agency that oversees the insurance program used by members of Congress and their families.

When Senate Majority Leader Harry Reid unveiled the compromise, he told reporters he could finally see the end in sight of the long struggle to overhaul the nation’s health care system. The measure under debate in the Senate would extend coverage to tens of millions who lack it, ban the insurance industry practice of denying insurance because of pre-existing medical conditions and generally rein in the skyrocketing cost of medical care nationally.

Democrats need 60 votes to overcome Republican opposition and pass the legislation, and optimism has seemed to increase since the Tuesday night announcement.

While Democrats worked privately to wrap up changes to the legislation, debate on the Senate floor was desultory. A proposal to permit the importing of prescription drugs from Canada and other countries as part of a cost-cutting move has been awaiting a vote since Tuesday, and none has been scheduled.

Political jousting did not rest, though, and at times, it verged on the personal.

When Reid outlined a proposed schedule under which the Senate would take the weekend off, Kentucky Sen. Mitch McConnell, the Republican leader, noted that there earlier had been plans to debate health care during that time.

Sen. John McCain, R-Ariz., spoke up, asking if it was possible to have a vote and adding, “I know New Orleans is very nice this time of year, but perhaps we ought to stay here and get this job done.”

That was a reference to a fundraiser Reid had scheduled for the weekend — an event the majority leader later said he had canceled.

But he got in a dig at Republicans, saying that Rush Limbaugh was “upset at Sen. McConnell because he’s not opposing the health care bill enough.”

McConnell has given over 75 speeches in recent months criticizing the Democratic health care plan. He has also worked behind the scenes to try and prevent any defections from the ranks of Republican opponents.