WASHINGTON — President Obama and House Democratic leaders worked furiously on Saturday to secure the votes needed to pass landmark health care legislation, with the outcome hinging on their effort to placate a small group of lawmakers who want the bill to include tighter limits on insurance coverage for abortions.
With the ground shifting by the hour, House Democratic leaders said they would drop a plan to approve the Senate health care bill without taking a direct vote on it — a maneuver that Republicans had denounced.
Instead, Democrats said they would first vote Sunday on a budget reconciliation bill including revisions to the Senate measure, and would then vote directly on the Senate bill itself. Many House Democrats had said they would oppose the Senate bill without changes.
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.
As Mr. Obama prepared to visit Capitol Hill for a meeting with House Democrats, Speaker Nancy Pelosi appeared to be within 10 votes of the 216 that she needs to approve the bill, with 21 Democrats still uncommitted. Republicans are all expected to oppose the bill, which is scheduled for a vote on Sunday.
On a day of high drama, with thousands of opponents of the health care legislation on the West Front of the Capitol chanting angry slogans, Ms. Pelosi expressed total confidence. “We will have the votes when we bring it to the floor,” she said, entering the House chamber on Saturday morning.
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 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 an executive order that would prohibit 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, however, 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 decided.
The official action on Saturday was in the House Rules Committee, which labored to set the formal terms of the debate for Sunday’s showdown.
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 health care 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 legislation would cost $940 billion over 10 years, according to the Congressional Budget Office, with the expense more than offset by revenues from new taxes, fees and reductions in spending on Medicare and other government programs. With those changes, the bill would reduce future deficits by $138 billion over that time period, the C.B.O. estimate found.
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.