Washington ? Jubilant Democrats locked in Nebraska Sen. Ben Nelson as the 60th and decisive vote for historic health care legislation Saturday, putting President Barack Obama’s signature issue firmly on a path for Christmas Eve passage.

At the White House, Obama swiftly welcomed the breakthrough, saying, “After a nearly century-long struggle, we are on the cusp of making health care reform a reality in the United States of America.”

In the Capitol, Senate Majority Leader Harry Reid smiled broadly when asked if Nelson’s decision gave him the 60-vote majority necessary to overcome solid Republican opposition. “Seems that way,” he said. The Nevada Democrat agreed to a series of concessions on abortion and other issues demanded by Nelson in daylong talks on Friday, then informed Obama of the agreement in a late night phone call as the president flew home from climate talks in Copenhagen.

The Congressional Budget Office said the Senate bill would extend coverage to more than 30 million Americans who lack it. It also imposes new regulations to curb abuses of the insurance industry, and the president noted one last-minute addition would impose penalties on companies that “arbitrarily jack up prices” in advance of the legislation taking effect.

CBO analysts also said the legislation would cut federal deficits by $132 billion over 10 years and possibly much more in the subsequent decade.

The developments unfolded on a day of improbables — a snowstorm enveloped the Capitol, creating whiteout conditions outside; while inside senators staged dueling news conferences as if their presence on the Saturday before Christmas was the rule rather than the rarest of exceptions.

At its core, the legislation would create a new insurance exchange where consumers could shop for affordable coverage that complied with new federal guidelines. Most Americans would be required to purchase insurance, with federal subsidies available to help defray the cost for lower and middle income individuals and families.

In a concession to Nelson and other moderates, the bill lacks a government-run insurance option of the type that House Democrats inserted into theirs. In a final defeat for liberals, a proposed Medicare expansion was also jettisoned in the past several days as Reid and the White House maneuvered for 60 votes.

Outnumbered Republicans unleashed a new series of attacks against the legislation and vowed to delay its passage as long as possible. The next — and most critical — test vote was set for about 12 a.m. Monday.

To secure passage, Democrats will need to show 60 votes on two additional occasions, and in the meantime, Reid made sure Republicans would have no additional chances to seek changes to the measure.

“This bill is a legislative train wreck of historic proportions,” the party’s leader, Sen. Mitch McConnell of Kentucky, said at a news conference. He pointed to cuts to Medicare that CBO said totaled more than $470 billion over a decade, with reductions in planned payments to home health care agencies and hospices. He also said the bill includes “massive tax increases” at a time of double-digit unemployment.

Many of Reid’s revisions were designed to secure the 60 votes needed to steer the bill past the GOP filibuster.

Those drafted at Nelson’s behest drew the most attention, and included further restrictions on abortion coverage in policies sold inside the exchanges.

States would be permitted to ban insurance coverage of abortions in policies sold in the exchange, except in cases of rape, incest or when the life of the mother is in jeopardy. In states where such coverage is permitted, consumers must notify their insurance company they want it, and pay for it separately.

Among the changes Reid incorporated was dropping a proposed tax on cosmetic surgical procedures, including Botox injections. Instead, Senate Democrats are proposing a 10 percent sales tax on tanning salons, to be paid by the person soaking up the rays. The Food and Drug Administration says ultraviolet radiation from tanning can increase the risk of skin cancer.