In the House, advocates and opponents of abortion rights and conservative Democrats have made clear that they object, for different reasons, to the Senate’s compromise language on abortion. Interest groups on both sides of the spectrum — Planned Parenthood on the abortion rights side, Catholic bishops for the anti-abortion rights camp — also oppose the abortion provision in the Senate bill, leaving Speaker Nancy Pelosi with a challenge in rounding up the votes she needs in the House.
Ms. Pelosi’s room for maneuvering is limited because any changes to the language in the Senate bill could unravel the deal that provided Democrats with the 60 votes they need to get the legislation through the Senate.
Ms. Pelosi, the Senate majority leader, Harry Reid of Nevada, and the White House will have to find a way forward on abortion even as they confront other big differences between the House and Senate bills, including how to pay to expand insurance coverage to more than 30 million Americans and whether to include a government-run plan to compete with private insurers.
The Senate bill cleared a major hurdle early Monday, when the Senate voted 60 to 40, along party lines, to limit debate on the guts of its measure. Two more votes are set for Tuesday. Calling it a “historic vote,” Mr. Obama said, “The United States Senate knocked down a filibuster aimed at blocking a final vote on health care reform, and scored a big victory for the American people.”
Senate Democrats got another lift on Monday when the American Medical Association endorsed their legislation, which embodies Mr. Obama’s top domestic priority.
“Of all the organizations and individuals that have supported this bill, I rate this one as the most important,” said Senator Christopher J. Dodd, Democrat of Connecticut and a co-author of the bill.
Jubilant and exhausted after winning the 1 a.m. test vote, Democrats on Monday were already thinking ahead to the next stage of the legislative process. The Senate and the House will try to hash out their differences, with members of the House under intense pressure to accommodate the tenuous deals in the Senate despite their ideological qualms. And no issue is shaping up to be more complex than abortion.
Representative Bart Stupak, Democrat of Michigan and the author of the anti-abortion provisions in the House bill, said Monday, “It would be extremely difficult for me to vote for a bill” taking the Senate approach on abortion.
The House, more liberal than the Senate on many issues, would impose more stringent restrictions, barring coverage of abortion by any health plan bought even partly with federal subsidies.
Under the bill that is likely to be approved this week by the Senate, health plans could cover abortion. But people who enroll in such plans would have to write two premium checks, one for abortion coverage and one for everything else. Insurers would have to keep separate accounts, and state officials would police the “segregation of funds.”
Douglas D. Johnson, legislative director of the National Right to Life Committee, said it was difficult to envision a compromise because “people opposed to abortion see it as the taking of innocent human life.”
Senator Barbara Boxer, Democrat of California, said Monday that the compromise she struck last week with Senator Ben Nelson, Democrat of Nebraska, offered a potential road map for successful negotiations on the issue with the House.
In an interview, Mrs. Boxer said the Senate bill created “a firm wall” that would prevent the use of federal money to pay for insurance coverage of abortions, meeting a demand of opponents of abortion rights, while allowing women to use their own money to buy health plans that cover the procedure.
“When you have both extremes saying they’re unhappy, I think it’s a fair compromise,” Mrs. Boxer said. “Because we have this compromise that’s being attacked on either side, I think that gives us momentum going into the final conference.”
Sixty-four House Democrats, representing one-fourth of the House Democratic caucus, voted for stringent restrictions on insurance coverage of abortion. And 41 of them voted for passage of the House bill, so they constitute a crucial bloc. The bill was approved, 220 to 215, on Nov. 7.
But leading supporters of abortion rights in the House said they would not vote for a final bill if it included those restrictions, which they fear would curtail access to abortion for many women who already have insurance.
The House bill would establish a tax surcharge on income over $500,000 for individuals and over $1 million for couples. The Senate bill would tax high-cost employer-sponsored health plans and increase the Medicare payroll tax on individuals with incomes over $200,000 and couples over $250,000.
Lawmakers said they could envision a compromise mixing the two approaches.
More than 190 House members have gone on record against the Senate’s proposed excise tax on “Cadillac health plans,” which is also opposed by organized labor. But the White House and some health economists say the tax could help control health costs by encouraging employers to shop for cheaper policies that would not be hit by the tax.
It is unclear whether the House and the Senate will appoint a formal conference committee or just try to work out their differences in negotiations with Democratic leaders and committee chairmen from the two chambers. In any event, White House officials expect to play a huge role.
The Senate may have the upper hand in negotiations on a government health plan, championed by liberal Democrats.
Senate Democratic leaders dropped the public option after concluding they could not get 60 votes for it. Their bill calls instead for two or more nationwide health plans, to be offered by private insurers under contracts negotiated with the federal Office of Personnel Management.
Ronald F. Pollack, executive director of Families USA, a liberal advocacy group that works closely with the White House, said Monday: “I think we will not have a public option in the final bill. It would be close to impossible to pass it in the Senate.”
On this, as on several other issues, Mr. Pollack said, “the Senate has somewhat greater leverage than the House” because Senate Democrats need 60 votes, the exact number in their caucus, to overcome Republican opposition.
Senator Joseph I. Lieberman, independent of Connecticut, said, “There is a natural tendency to split the difference between the Senate and the House.” But on major issues in the health bill, Mr. Lieberman said, “splitting the difference means you won’t have 60 votes in the Senate.”
In the eyes of consumers and voters, the success of the legislation will hinge, to a large degree, on whether it makes insurance more affordable. One of the most important issues for House and Senate negotiators is how to aid low- and middle- income people.
The House would expand Medicaid to cover people with incomes less than 150 percent of the poverty level ($33,075 for a family of four). The Senate would expand eligibility to 133 percent of the poverty level ($29,327 for a family of four). Many advocates for low-income people prefer the House approach.