WASHINGTON — With the stage set for a historic showdown over landmark health legislation in the House on Sunday afternoon, the White House and Democratic Congressional leaders winnowed their hunt for votes to a slim list of lawmakers, including several opponents of abortion who were demanding assurance that no federal money would be used to pay for insurance coverage of the procedure.
Democrats late Saturday night said the 216 votes needed to pass the bill were nearly within their reach, but acknowledged that the margin of victory would likely be razor thin even under their most optimistic scenario. Republicans said they still held out hope of derailing the legislation.
Shortly before midnight on Saturday, the House Rules Committee completed its work and proposed the parameters for Sunday’s floor fight, which will entail two hours of formal debate on the legislation. The committee, controlled by Democrats, also limited the ability of Republicans to disrupt the proceedings and allowed for the vote to be postponed if Democrats chose to do so.
President Obama, in an emotional address Saturday afternoon at the Capitol, exhorted rank-and-file House Democrats to approve the bill, telling them they were on the edge of making history.
“Every once in a while a moment comes where you have a chance to vindicate all those best hopes that you had about yourself, about this country,” he said. “This is one of those moments.”
The president declared: “We have been debating health care for decades. It has now been debated for a year. It is in your hands.”
With the ground shifting by the hour, House Democratic leaders dropped a plan to approve the Senate health bill without taking a direct vote on it. That proposed maneuver had outraged Republicans and caused consternation among some Democrats.
Thousands of opponents of the bill circled the Capitol chanting angry slogans. Some of the anger was directed at black lawmakers, including several who said that some demonstrators had hurled racial insults at them.
Speaker Nancy Pelosi refused to give abortion opponents a separate vote on that issue, a sign of her confidence that she could clinch the votes without further changes to the bill.
Democrats said they would vote Sunday on the Senate bill and on revisions to it included in a budget reconciliation measure.
Democrats said the outcome would be the same: the Senate bill would be sent to Mr. Obama, who would sign it into law, and the reconciliation bill would go to the Senate, which could take it up within days.
At the Capitol rally with Mr. Obama, the Senate majority leader, Harry Reid of Nevada, assured House Democrats that their Senate colleagues would act quickly on the reconciliation bill, including final revisions to the health care measure. “I have the commitments of a significant majority of the United States Senate to make that good law even better,” he said.
As Mr. Obama concluded his remarks, Ms. Pelosi appeared to be within 8 votes of the 216 she needed to approve the bill, with 19 Democrats still uncommitted. Republicans are all expected to oppose the bill.
The House Republican leader, John A. Boehner of Ohio, said the Republicans could still prevail. “The American people are making their voices heard, here on Capitol Hill and across America,” he said. “It’s time for Washington Democrats to listen.”
In his speech, Mr. Obama drew chortles from lawmakers — and laughed at himself — when he suggested that perhaps Republicans were hoping to spare Democrats political pain by blocking the bill.
“Mitch McConnell, John Boehner, Karl Rove, they are all warning you of the horrendous impact if you support this legislation,” the president said, referring to the Senate and House Republican leaders and a top adviser to former President George W. Bush.
“Now, it could be that they are suddenly having a change of heart and they are deeply concerned about their Democratic friends; they are giving you the best possible advice in order to ensure that Nancy Pelosi remains speaker and Harry Reid remains leader and all of you keep your seats,” Mr. Obama joked. “That’s a possibility.”
He continued, “But it may also be possible that they realize that after health reform passes and I sign that legislation into law, it’s going to be a little harder to mischaracterize what this legislation has been all about.”
Ms. Pelosi expressed total confidence in the bill’s prospects. “We are on the verge of making great history for the American people,” she said.
The speaker on Saturday rejected a proposal by Representative Bart Stupak, Democrat of Michigan and a leader of the abortion opponents, to revise the abortion provisions after the bill was adopted, a step that is typically used to make minor or technical changes and that requires approval of both the House and the Senate.
Instead, Democratic officials said they were pursuing the idea of promising that Mr. Obama would issue an executive order prohibiting the use of taxpayer money for abortions. They said that approach would not mollify Mr. Stupak but could win the support of others still undecided because of their views on abortion.
Ms. Pelosi said she would not allow separate votes on abortion or other controversial issues. “Not on abortion, not on public option, not on single-payer, not on anything,” she said.
Behind the scenes, Ms. Pelosi was working aggressively to address the concerns of anti-abortion Democrats. She met with at least three of those lawmakers — Representatives Christopher Carney and Kathy Dahlkemper of Pennsylvania and Steve Driehaus of Ohio — none of whom had publicly committed their vote.
Before Democrats decided to take a direct vote on the Senate health care bill, Representative Joe L. Barton, Republican of Texas, described the plans to approve it without a direct vote as “a sleight-of-hand subterfuge” that would allow lawmakers to avoid accountability.
“This process corrupts and prostitutes the system” and could “unleash a cultural war” over the legislation, Mr. Barton said.
Democrats, however, tried to keep the focus on the substance of the legislation, which seeks to extend coverage to 32 million uninsured Americans.
“We are on the verge of taking a decisive step to providing access to all Americans to affordable quality health care,” said Representative Henry A. Waxman, Democrat of California and chairman of the Energy and Commerce Committee. “If we do nothing, the system will go bankrupt, premiums will keep skyrocketing and benefits will keep getting slashed.”
The Congressional Budget Office on Saturday released a new cost analysis of the legislation based on a package of changes unveiled by the Democrats earlier in the day. The new assessment shows the total cost of new insurance coverage provisions in the bill to be $938 billion over 10 years, with the expense more than offset by revenues from new taxes and fees and reductions in spending on government programs including Medicare, so that the legislation would reduce future federal deficits by $143 billion. The previous budget office estimate showed a total cost of $940 billion for the coverage provisions, and $138 billion in deficit reduction.
At a news conference on Saturday, 13 House Republican freshmen assailed the measure. “Let’s kill this bill,” said Representative Cynthia M. Lummis, Republican of Wyoming.
The late-hour maneuvering on abortion mirrored a similar process in November before the House adopted its version of the health care legislation.
In November, however, Mr. Stupak succeeded in winning approval of tight limits on insurance coverage of abortions in the House bill. The current package now includes language from the bill passed in the Senate and negotiated by two Democrats, Senators Bob Casey of Pennsylvania and Ben Nelson of Nebraska, who have built up solid credentials in their political careers as abortion opponents.
Once again, Mr. Stupak was opposed by a group of lawmakers who favor abortion rights, led by Representative Diana DeGette, Democrat of Colorado. And once again, at the center of the storm was Ms. Pelosi, the first woman to serve as House speaker, who is a champion of abortion rights.
The abortion issue has divided Roman Catholic groups in the United States, with the United States Conference of Catholic Bishops opposing the bill and other organizations, including the Catholic Health Association and a coalition of nuns from leading religious orders, favoring it.
Mr. Stupak and many of the lawmakers insisting on the tighter restrictions are Catholic, as is Ms. Pelosi, and all have cited their faith in justifying their position on the legislation.
In a sign of the emotion around the issue, Representative Dale E. Kildee, Democrat of Michigan, who is Catholic and opposes abortion, announced his support for the legislation in a statement pointing out that he had once studied for the priesthood. He said he had consulted his priest and concluded that the abortion restrictions in the Senate bill were sufficient.
Democratic leaders said they hoped an executive order by Mr. Obama would clarify that the legislation was not intended to change existing federal law and policy that generally bar the use of taxpayer money for abortions.
“That is very good if the president does that,” said Representative Lynn Woolsey, Democrat of California and co-chairwoman of the Congressional Progressive Caucus. “He will clear it up. The Senate bill does not allow federal funds to be used for abortion.”
But Representative Anh Cao of Louisiana, the only Republican who voted for the bill in November, said he could not support the current measure because of its “expansion of abortion, an absolute moral evil.”
Democratic lawmakers and top aides have been working round the clock trying to address flare-ups over elements of the bill. They said they had worked out an agreement to resolve one of the last remaining issues: a dispute over geographic disparities in Medicare payments.
The agreement could lead to higher payments to doctors and hospitals in states like Iowa, Minnesota, Oregon, Washington and Wisconsin, where Medicare rates are relatively low but studies suggest that the quality of care is high.
Kathleen Sebelius, the secretary of health and human services, sent a letter to Congress saying she would commission studies by the National Academy of Sciences to investigate the issue and recommend solutions.
“The current geographic variation in Medicare reimbursement rates is inequitable,” Ms. Sebelius said.
Outside the Capitol on Saturday, several House members said, there was an ugly tone to comments made by some demonstrators against three black lawmakers: Representatives André Carson of Indiana, Emanuel Cleaver II of Missouri and John Lewis of Georgia, all Democrats.
An aide to Mr. Lewis, a leader of the civil rights movement in the 1960s, said that as he walked to the Capitol, racial slurs were shouted at Mr. Lewis. A spokesman for Mr. Cleaver said that a protester spat on the congressman as he was walking to the Capitol for a vote.
Carl Hulse contributed reporting.