WASHINGTON — As House Democrats geared up for a possible vote on Sunday to pass health care legislation, the Congressional Budget Office issued an analysis allowing them to point to significant cost savings in the decades ahead, and President Obama postponed a planned trip to the Pacific to keep pressing for approval.

The House Democratic leader, Rep. Steny H. Hoyer of Maryland, said that the nonpartisan budget office had determined that the package of legislation, which would cost about $940 billion over ten years, would produce “the largest deficit reduction of any bill we have adopted in Congress since 1993,” when it passed tax increases sought by President Clinton.

In the first ten years, the health legislation would reduce deficits by $138 billion,and the effect on deficits over the following decade would be much greater — Democrats said $1.2 trillion — although such long-term forecasts are more speculative. The savings would come largely from reductions in the growth of Medicare spending, with new fees and tax increases also contributing.

The cost savings are “but one virtue of a reform that will bring new accountability to the insurance industry and greater economic security to all Americans,” President Obama said at a ceremony where he signed a new jobs bill into law. “So I urge every member of Congress to consider this as they prepare for their important vote this weekend.”

The White House said Mr. Obama has decided not to leave for the Pacific on Sunday, the second such delay in his travel plan, in order to maintain full attention on health care. His planned visit to Indonesia, Australia and Guam will instead take place in June, the White House said.

“The president greatly regrets the delay,” said his spokesman, Robert Gibbs. “Passage of the heath insurance reform is of paramount importance, and the president is determined to see this battle through.”

The full text of the legislation, which would put the final touches on a delicate compromise between the House and the Senate, was to be issued later on Thursday, House Democrats said.

The bill passed by the Senate in December would have reduced deficits by somewhat less — $118 billion — according to the budget office, whose estimates are considered authoritative. House leaders, who are seeking first to adopt that Senate bill as written and then to fine tune it with a second bill that could be approved by the Senate with a simple majority vote, had spent the past week or two crunching the numbers with the budget office in order to make the best possible fiscal case to their nervous caucus.

The cost of the legislation has been a major concern for many centrist Democrats, a crucial bloc for leaders who are trying to muster the majority to pass the bill.

“We are absolutely giddy over the great news,” said the House’s number three Democrat, Rep. James Clyburn of South Carolina, who as the party whip is the keeper of its vote tallies.

But Republicans moved quickly to throw cold water on the claims, noting that government debt is piling up so fast that the health care legislation would barely make a dent. “Any projected savings, over 10 years, have already been wiped out five times over in just the first five months of the current fiscal year,” said Don Stewart, a spokesman for the Senate Republican leader, Mitch McConnell of Kentucky.

Mr. Stewart cited budget office data showing that the federal government had “incurred a budget deficit of $655 billion in just the first five months of fiscal year 2010.”

The debt incurred in the 2010 fiscal year includes some spending for last year’s economic stimulus package, in response to the severe recession.

House Democrats locked in two more votes Wednesday, giving them added confidence as they worked out the last details of the bill and girded for a showdown with Republicans Behind the scenes, Democratic leaders were still working to secure backing for the legislation from among roughly three dozen members of the party whose votes are considered to be in play.

But they sought to portray the measure as gaining momentum from the public declarations of support from two Democrats: Dennis J. Kucinich of Ohio, who had previously opposed it, and Dale E. Kildee of Michigan, who had been among a group seeking tighter restrictions on the financing of insurance covering abortions.

Democratic leaders say they have not yet nailed down the 216 votes they need for passage, but they are pressing ahead in the belief that they can get them. Mr. Hoyer said the House could take a final vote on the legislation by Sunday.

The endorsement from Mr. Kucinich suggested that Democrats who have been pushing for more ambitious legislation might put aside their reservations and unite behind the bill as their best opportunity to secure health insurance for millions of Americans who now lack it. The backing from Mr. Kildee — and new support from nuns who lead major Roman Catholic religious orders — indicated that Democrats were having some success in addressing an issue that has cost the votes of some Democrats who oppose abortion rights.

But House Republicans said they still believed they could block the bill, a top priority for President Obama and Speaker Nancy Pelosi.

Under a two-step plan devised by House Democratic leaders, the House would approve the health care bill passed by the Senate in December, then make changes in a separate bill using a procedure known as budget reconciliation to avoid the threat of a filibuster in the Senate. Republicans like Representative David Dreier of California have accused Democrats of ducking a straight-up vote on the Senate bill, which has provisions that many House Democrats do not like.

In an interview with Fox News, Mr. Obama dismissed Republican criticisms of the parliamentary tactics, saying he does not “spend a lot of time worrying about what the procedural rules are.”

“What I can tell you is that the vote that’s taken in the House will be a vote for health care reform,” Mr. Obama said. “And if people vote yes, whatever form that takes, that is going to be a vote for health care reform.”

Mr. Obama likened the measure to fixing the financial system or passing the economic recovery act. “I knew these things might not be popular, but I was absolutely positive that it was the right thing to do,” he said.

Representative John A. Boehner of Ohio, the House Republican leader, said Republicans were engaged in a variety of activities to stir opposition to the health care bill in the home districts of Democrats considered vulnerable in the November elections.

“We are going to do everything we can to put the pressure on these guys because they are going to have to choose,” said Mr. Boehner. “Are they going to vote with Nancy Pelosi and the president, or are they going to vote with their constituents?”

“It’s going to be a wild ride,” Mr. Boehner predicted.

Besides securing commitments from Mr. Kucinich and Mr. Kildee, House Democratic leaders said they were pleased at the prospect of winning support from Representative James L. Oberstar, Democrat of Minnesota and an opponent of abortion.

John A. Schadl, a spokesman for Mr. Oberstar, said the congressman was “a strong likely yes” on the health care bill. Mr. Schadl said Mr. Oberstar was generally satisfied that the bill before the House would not allow the spending of federal money on abortion.

Democrats had hoped to unveil the text of the reconciliation bill on Wednesday afternoon, setting up the possibility of a decisive vote on Saturday, but the Congressional Budget Office was not yet finished analyzing the cost of some provisions.

House Democratic leaders have promised that lawmakers would be given 72 hours to review the legislation before voting on it.

The No. 2 Democrat in the Senate, Richard J. Durbin of Illinois, said the Senate could pass the reconciliation bill as soon as next week if the House approves it over the weekend.

In announcing his support, Mr. Kucinich said he would keep working for a government-financed single-payer health care system. But after coming under intense pressure, which included a visit to his district on Monday by Mr. Obama, Mr. Kucinich said he did not want his objections to stand in the way of the legislation.

“If my vote is to be counted, let it count now for passage of the bill, hopefully in the direction of comprehensive health care reform,” Mr. Kucinich said.

Explaining factors he had considered in making his decision, Mr. Kucinich said, “We have to be very careful that the potential of President Obama’s presidency not be destroyed by this debate.”

“Something is better than nothing — that’s what I keep hearing from my constituents,” Mr. Kucinich said.

A last-minute hitch developed Wednesday over a couple of provisions of the Senate bill of great interest to organized labor.

One provision singles out the construction industry for special treatment, in a way that benefits union members and contractors who use union labor. It was unclear whether that provision had survived in the final package, and on Wednesday, Richard L. Trumka, the president of the A.F.L.-C.I.O., met with Mr. Obama at the White House to discuss the issue.

Labor leaders are also concerned about a provision of the Senate bill that would impose an excise tax on high-cost employer-sponsored health plans. In January, Mr. Trumka and the White House reached an agreement that would delay the tax to 2018 and reduce the number of health plans affected.

Republican senators said they believed they could successfully challenge the inclusion of that agreement in the final health care package, on the ground that it would violate the rules for budget reconciliation. If the compromise is dropped from the bill, labor groups and some of their allies on Capitol Hill would be much less supportive of the bill.

At the same time, Democrats said they were making progress on the divisive issue of abortion.

Mr. Kildee voted for the House health care bill in November, after Representative Bart Stupak, also a Michigan Democrat, won passage of an amendment imposing tight restrictions on insurance coverage for abortions.

Mr. Stupak has said he will vote against the Senate bill because he sees the restrictions on abortion as inadequate. But Mr. Kildee said he was satisfied that the provisions in the Senate bill would prevent the use of federal money for coverage of abortions.

“I have always respected and cherished the sanctity of human life,” Mr. Kildee said. “I spent six years studying to be a priest and was willing to devote my life to God.”

“I have listened carefully to both sides, sought counsel from my priest, advice from family, friends and constituents, and I have read the Senate abortion language more than a dozen times,” Mr. Kildee said. “I am convinced that the Senate language maintains the Hyde Amendment, which states that no federal money can be used for abortion.”

Mr. Stupak reiterated his opposition to the Senate bill, as did the United States Conference of Catholic Bishops.

But in a letter to House members on Wednesday, more than 50 nuns from various religious orders said, “The time is now for health reform, and the Senate bill is a good way forward.”