The nonpartisan Congressional Budget Office said that Majority Leader Harry Reid's 10-year, $848-billion bill would produce a net reduction of $130 billion in federal deficits in its first decade. Perhaps more significantly, the legislation would continue to give back over the next 10 years and beyond, the budget umpires said, because "added revenues and costs savings would probably be greater" than the cost of covering uninsured Americans.
The budget office put a big asterisk on its forecast, using words like "imprecision" and "uncertainty" to describe the long-range projection. It noted that, overall, health care spending remains on an unsustainable path.
However, the bill would not make matters any worse, and maybe even a little better.
With President Barack Obama pledging to tamp down ruinous health care costs, Democrats took the new CBO estimates to the bank, while skipping over the caveats. Preparing for a noontime rally with supporters, Reid, D-Nev., said the legislation would "save lives, save money and save Medicare."
The CBO said Reid's bill would extend coverage to 94 percent of eligible Americans, after subsidies to make premiums more affordable start flowing in 2014. That's one year later than in the House Democratic bill - and well into the next presidential term. Postponing the subsidies by one year allowed Reid to offer somewhat more generous assistance to defray the cost of insurance premiums.
On one of the major controversies of the health care debate, the CBO said Reid's bill would make a government health plan widely available - but few Americans would sign up.
About two-thirds of the U.S. population would have a public plan available in their state, even though the bill would allow individual states to opt out. Still, only 3 million to 4 million people would sign up, partly because private insurance plans would still be able to offer lower premiums.
While most Americans would get to observe the new experiment with government coverage in their states, few would actually participate.
Facing a key floor vote Saturday, Republicans remained unflinching in their opposition.
"Now it's America's turn, and this will not be a short debate," warned Sen. Mitch McConnell of Kentucky, the Republican leader. "Higher premiums, tax increases and Medicare cuts to pay for more government. The American people know that is not reform."
Reid's bill relies on cuts in future Medicare spending to cover costs, as well as on higher payroll taxes for the well-off, a new levy on patients undergoing elective cosmetic surgery, and a laundry list of other taxes, fees and penalties.
The Democratic leader wrote the legislation with White House aides during weeks of secretive negotiations, selecting elements from two committee-passed bills with the aim of securing the necessary 60 votes in a Senate debate that will be decisive for Obama's health care agenda.
Democrats hold 58 seats in the Senate and two independents generally vote with them, but several moderate Democrats - Mary Landrieu of Louisiana, Ben Nelson of Nebraska and Blanche Lincoln of Arkansas - have yet to commit to allowing debate to begin. Reid met privately with the three before releasing his bill Wednesday, and Nelson later issued a statement strongly suggesting he would support fellow Democrats on the procedural vote.
Reid has pointedly declined to claim the 60 votes needed to clear a must-pass procedural hurdle this weekend before debate can begin. But Sen. Tom Harkin, D-Iowa, says he believes the wavering moderates will side with their party on procedural votes. Whether they vote for the final bill in the end is less certain.
"I believe we'll stick together ... this is team effort," said Harkin. "No one Democrat is going to want to stand out there and say, 'Stop this."'
The mammoth, 2,074-page bill would, for the the first time, require most Americans to carry health insuranc. It would provide hundreds of billions of dollars in subsidies to help those with lower incomes afford coverage.
Employers would not be required to offer coverage, but medium and large companies would pay a fee if the government ends up subsidizing employees' insurance.
Beginning in 2014, Reid's bill would set up new insurance marketplaces called exchanges, primarily for those who now have a hard time getting or keeping coverage. Consumers would have the choice of purchasing government-sold insurance, an attempt to hold down prices charged by private insurers.
If this weekend's vote succeeds, it would be followed by weeks of unpredictable maneuvering on the Senate floor, where Reid and his allies will seek to incorporate changes sought by Democrats and repel attempts by Republicans to defeat the legislation and inflict a significant political defeat on the president.
On a controversial issue that threatened to derail the House-passed bill, Reid would allow the new government insurance plan to cover abortions and would let companies that receive federal funds offer insurance plans that include abortion coverage.
A provision in the House bill - passed at the insistence of anti-abortion Democrats over strenuous objections from liberals - banned both those things. Reid attempted to tighten up the abortion language to strictly segregate private from public funds, but that did not pass muster with the National Right to Life Committee, which issued a statement Wednesday night calling the language "completely unacceptable."
Associated Press writers David Espo and Ken Thomas contributed to this report.