"I believe in my heart of hearts that this handles the whole question of funding abortion," Nelson told reporters Saturday morning, saying that he did not believe the bill was perfect, but that he thought it was important to keep moving.
Boxer and other abortion rights advocates also expressed support. "We said all along that we wanted to ensure there was a firewall between private and public funds -- this compromise achieves that," Boxer and Sen. Patty Murray of Washington state, the No. 4 Democrat in the Senate, said in a joint statement
GOP lawmakers and some antiabortion groups immediately lambasted the compromise, which Oklahoma Sen. Tom Coburn said "threw unborn babies under the bus."
The changes were incorporated into a 383-page amendment that Reid used to accommodate the many demands of members of his diverse caucus.
Reid's changes, the so-called manager's amendment, would increase spending slightly but still would reduce the deficit $2 billion further than the original legislation, pushing savings to $132 billion over the next decade, according to the nonpartisan Congressional Budget Office.
The most politically explosive change is the elimination of a new government insurance plan for Americans who do not get insurance through work, a long-cherished dream of the left.
Instead of that "public option," the modified bill would authorize the federal government to contract with two insurers, one a nonprofit, to provide consumers nationwide with alternatives to plans offered by the private market.
The insurers would be subject to an additional level of federal oversight to ensure that they offered quality, affordable coverage.
That change pleased conservative Democrats wary of a new government program.
Reid's modified bill would tighten regulations on insurers, requiring them to commit at least 80% of their annual expenses to paying medical claims -- and at least 85% for insurers that sell plans to large companies.
At the request of Sen. Dianne Feinstein (D-Calif.), the bill would also give state and federal officials greater authority to regulate how much insurance companies raise their premiums each year, a provision that consumer advocates consider crucial because the legislation would require almost all Americans to buy health insurance.
Reid did not slash a proposed tax on high-cost "Cadillac" health plans, despite pleas from labor unions, which fear the tax would hit many of their members, who have given up wage hikes over the years in exchange for more-generous health benefits.
The bill imposes a 40% tax on every dollar of insurance premiums above $8,500 a year for individuals and $23,000 for families, with some exceptions.
Reid also further boosted the Medicare payroll tax, from 1.45% to 2.35%, on individuals who make more than $200,000 and couples who make more than $250,000.
Kim Geiger in the Washington bureau contributed to this report.