WASHINGTON - The Senate was poised late yesterday to take a giant step closer to enacting a sweeping health-care bill - a watershed moment that finally has united a fractious Democratic majority after months of debate over President Obama's promise to provide universal health-care coverage.

The move to break a Republican filibuster, which required winning the votes of all 60 members of the Democratic caucus in a dramatic vote scheduled for 1 o'clock this morning, capped months of work by Obama and Senate Majority Leader Harry Reid (D., Nev.). They personally forged politically necessary compromises on big issues such as abortion and taxes, as well as parochial deals for favored states and industries.

Striking the death knell for Obama's hope for at least token bipartisan support, Sen. Olympia Snowe of Maine, the one Republican who even considered supporting the bill, yesterday announced she opposed it.

"I deeply regret that I cannot support the pending Senate legislation as it currently stands, given my continued concerns with the measure and an artificial and arbitrary deadline of completing the bill before Christmas that is shortchanging the process on this monumental and transgenerational effort," she said.

Her Maine colleague, Republican Susan Collins, also announced her opposition.

But with final Senate approval of the bill expected this week, Democrats and the White House moved yesterday to shift the focus away from the dozens of concessions made in writing the bill and toward the momentous changes it will bring:

Bestowing access to insurance on 31 million Americans, cracking down on mercurial insurance practices, and beginning to curb unsustainable medical inflation.

"I wish this bill were different," Assistant Majority Leader Richard J. Durbin (D., Ill.) said on the Senate floor yesterday, reflecting liberals' unhappiness over some of the compromises with conservative members of their party.

"But my disappointment . . . shouldn't lead me to conclude that this bill is wanting or this bill is bad. Just the opposite is true. . . . We have to look at the positive side of what this legislation will do."

The bill's progress provides a shot of adrenaline for Obama and the Senate Democrats as opinion polls indicate the public's support for the overhaul is waning. Hoping to reverse that slide, Democrats and the White House ramped up efforts yesterday to reshape public perception of the bill as a glass half full, not half empty.

"This is a historic crossroads," David Axelrod, senior Obama adviser, said on NBC's Meet the Press. "Seven presidents have tried to pass comprehensive health insurance reform, seven presidents have failed. We're on the doorstep of getting it done."

Shifting the focus on how much change the bill would deliver will be particularly important as key lawmakers in the House and Senate begin another arduous round of compromising and deal-making to reconcile differences between the health-care bills developed in the two chambers.

The Senate's planned first vote to shut down the Republican filibuster capped a weekend session that marked the third time in the last month the Senate has met on Saturday and Sunday.

Two more procedural votes to close debate - tomorrow and Wednesday - will be taken before the bill comes to a final vote.

Republicans, while united in opposition, conceded they were powerless to derail the bill. But they vowed to force the debate to continue as long as possible - probably until Christmas Eve.

"We will fight until the last vote," Sen. John McCain (R., Ariz.) said on Fox News Sunday. "We must do everything. We must look back and say, 'We did everything we can to prevent this terrible mistake from taking place.' "

Other Republicans turned a spotlight on the special deals cut to win the support of Sen. Ben Nelson (D., Neb.), who provided the last vote Reid needed after winning special treatment for his state's Medicaid program, changes sought by insurance companies in Nebraska, as well as tighter restrictions on federal funding for abortion.

That kind of horse-trading is common in Congress, but Republicans said it was unseemly in a bill of such far-reaching implications.

"This process is not legislation," declared Sen. Tom Coburn (R., Okla.) "This process is corruption."

Democrats emphasized the broader provisions of the bill that provide direct benefits to consumers, including major changes eclipsed in the final stages of the debate.

Among them, the Senate bill includes a "patients bill of rights" - consumer protections that, when they were considered on their own more than a decade ago, died amid heated controversy.

The bill also would require insurance companies to apply more of their premium income to patient services, not profits or administrative costs.

That was an important consolation prize for liberals who sought a government insurance program in large part to provide competition for private insurers.

"Now they must be accountable to consumers and spend more of their hard-earned dollars on actual health care and not on filling their coffers," said Sen. John D. Rockefeller 4th (D., W.Va.), who has led investigations of the health insurance industry.

Democrats hope the more the public knows about those and other benefits in the bill, the more they will like it.