A day after Senate Democrats said that they had clinched an agreement on a far-reaching overhaul of the nation’s health care system, Republicans vowed on Sunday to continue their fight while acknowledging that their chances of stopping Senate passage had faded.
Asked whether he and his fellow Republicans could yet block the bill, John McCain of Arizona seemed resigned to its passage.
“Probably not,” he replied on “Fox News Sunday.” “We’ll fight the good fight, we‘ll fight until the last vote.”
If the Senate bill passed, it would have to be reconciled in conference with the earlier House version. The two differ substantially; and a key senator said Sunday that it would be difficult for his chamber to pass anything that varies much from the Senate version.
But on Saturday, Democratic leaders hailed as a breakthrough the agreement by Senator Ben Nelson, Democrat of Nebraska, to back the bill after 13 hours of negotiations.
He was the pivotal 60th vote for a measure that President Barack Obama has called his top domestic priority; it would significantly overhaul the country’s health care system, extending health benefits to more than 30 million uninsured Americans.
The Senate plans a crucial procedural vote at 1 a.m. Monday and a final vote on Dec. 24, allowing scant time to review the bulky and complicated bill or a last-minute 383-page amendment that reflects the Nelson agreement.
Senator Jon Kyl, a conservative Republican from Arizona, charged Sunday on ABC’s “This Week” that Democrats were using the imminent Christmas holiday to force a quick vote on a bill that he said Democrats were trying to sell “on an artifice.”
The measure would extend health benefits by expanding Medicaid and providing subsidies to help moderate-income people buy private insurance. It would require nearly all Americans to obtain insurance or pay financial penalties for failing to do so.
Republicans say the bill would spell disaster, raising taxes and hurting families and small businesses by increasing health care costs over the long term and reducing medical services for older patients.
Congressional Budget Office said the legislation would cost $871 billion over 10 years, with the expense more than offset by revenues from new taxes and fees and by reductions in government spending, particularly on Medicare. The budget office said the bill would reduce future deficits by $132 billion over that period.
Republicans were sharply critical, pointing to the fact that some benefits would take effect only years after new taxes and fees kicked in.
“That is budget gimmickry, and we all know it,” said Mr. McCain, the 2008 Republican presidential nominee.
Republicans say Democrats are using accounting tricks to hide the true cost of the measure, which they predicted would be huge.
Democrats described the legislation as historic.
“After nearly a century-long struggle,” Mr. Obama said Saturday from the White House, “we are on the cusp of making health care reform a reality in the United States of America.”
Mr. Nelson committed his vote after winning tighter restrictions on insurance coverage for abortions, as well as increased federal health care aid for his state — special treatment denounced by Republicans.
He pointedly warned, however, that he would oppose the final version if negotiations with the House, which approved its bill last month, yield changes that he does not like.
House liberals are expected to resist some concessions made in the Senate. To secure the votes of centrist holdouts, Senate leaders dropped the proposed government-run health insurance plan, or public option, which was favored by liberals.
Instead, the Senate bill would create at least two national insurance plans modeled after those offered to federal workers. The bill bars insurers from denying coverage based on pre-existing medical conditions.
Senator Kent Conrad, Democrat of North Dakota and chairman of the powerful Budget committee, said Sunday that there was little room for compromise with the House.
“It is very clear that the final bill, to pass in the United States Senate, is going to have to be very close to the bill that has been negotiated here,” he said on “Fox News Sunday.” “Otherwise it will not get 60 votes.“
The Democrats nominally control the 60 Senate seats needed to overcome a Republican filibuster. No Republican has been willing to support the legislation.
Under the deal with Mr. Nelson, health insurance plans would not be required or forbidden to cover abortions, but states could prohibit the coverage of abortions by plans that are offered for sale through new government-regulated marketplaces.
Brian Knowlton and Robert Pear contributed reporting.
This article, "," first appeared in The New York Times.