Even an expansion of Medicare, initially proposed as a backup to the government option, appeared unlikely to survive following a closed-door senators-only meeting called to consider trade-offs necessary to assure 60 votes for the bill.
According to a report by Politico.com, the president will impress upon his fellow Democrats that this is the "last chance" to get a bill done.
"If President Obama doesn't pass health reform, it's hard to imagine another president ever taking on this Herculean task. For those whose life's work is reforming health care, this may be the last train leaving the station," White House communications director Dan Pfeiffer told Politico.
Bob Schieffer: Make or Break Time for Dems? Not Yet
"Put me down tonight as encouraged about the direction these talks are going," Sen. Joe Lieberman, I-Conn., said late Monday, only 24 hours after he rattled Democrats by threatening to oppose the .
However, nobody knows what's in the bill because Democrats are still in the process of adding and subtracting measures until they hit on something 60 senators can agree to, reports CBS News correspondent Nancy Cordes.
Democrats say they are confident they can fashion a deal before the holidays, but they've been saying that for weeks and there's still no agreement, notes Cordes.
Mr. Obama invited all Senate Democrats to the White House for a meeting Tuesday afternoon that held promise of a unity event. Mr. Obama needs every one of them to hang together to give him the 60 votes required to overcome stalling tactics from Republicans united in opposition to the sweeping health overhaul measure.
Majority Leader Harry Reid, D-Nev., promised to deliver.
"I'm confident that by next week we will be on our way toward final passage of a bill that saves lives, saves money and saves Medicare," Reid told reporters after Monday night's meeting.
CBSNews.com Special Report: Health Care Reform
Liberals had sought the Medicare expansion as a last-minute substitute for a full-blown, government-run insurance program that moderates insisted be removed from the legislation. But it drew strong opposition from Lieberman and quieter concerns from other Democrats - all of whom hold votes essential for passage.
Reid did not say flatly that Democrats had decided to drop the proposal for uninsured Americans as young as 55 to purchase coverage under Medicare, the government program now open to people when they turn 65. But several senators said it appeared inevitable.
"We're not going to get all that we want but we're going to get so much more than we have," liberal Sen. Jay Rockefeller, D-W.Va., said.
The overall measure, costing nearly $1 trillion over a decade, is designed to expand coverage with a new requirement for nearly everyone to purchase health insurance, and ban industry practices such as denying coverage on the basis of pre-existing medical conditions. Mr. Obama also has urged Congress to slow the growth in health care spending nationally; several days after Reid submitted a package of revisions, lawmakers awaited final word from the Congressional Budget Office on that point.
Disputes over abortion and the importation of prescription drugs from Canada and other countries also simmered as the Senate entered a third week of debate on the legislation.
In a gesture that Democrats said was aimed at the AARP, Reid promised that any final compromise with the House would completely close a gap in Medicare prescription drug coverage generally known as the "doughnut hole." The Senate bill goes only part way toward that goal.
Less than an hour after Reid spoke, AARP CEO A. Barry Rand issued a statement thanking the Nevada Democrat.
Sen. Byron Dorgan, D-N.D., led the effort to lift a long-standing ban on the importation of prescription drugs from Canada and elsewhere. Mr. Obama favored the plan as a senator, but the pharmaceutical industry is opposed, and the White House appeared anxious not to jeopardize a monthslong alliance with drug makers who have been helpful in trying to pass the overhaul. A vote was set for late Tuesday.
The obstacle that loomed largest was the Medicare expansion proposal, vestige of a monthslong debate over the role of government in the newly revised health care system. It emerged last week as part of a framework agreement between moderates and liberals. Additionally, the proposal calls for creation of nationwide plans run by private insurance companies under the supervision of the Office of Personnel Management, which oversees health plans for members of Congress and other federal workers.
The two provisions were seen as a replacement for Reid's initial call for a government-run insurance plan to compete with private industry, a liberal priority opposed by moderates as an unwanted government intrusion. The one unrelated to Medicare is expected to survive, but without standby authority for the OPM to set up a government-run plan if no private coverage options materialize.
Opposition to the Medicare change blossomed from doctors and hospitals, who are paid less to treat Medicare patients than those covered by private insurance companies.