By Raymond Hernandez

WASHINGTON — After years of fierce lobbying and debate, Congress approved a bill on Wednesday to cover the cost of medical care for rescue workers and others who became sick from toxic fumes, dust and smoke after the 2001 attack on the World Trade Center.

The $4.3 billion bill cleared its biggest hurdle early in the afternoon when the Senate unexpectedly approved it just 12 days after Republican senators had blocked a more expensive House version from coming to the floor of the Senate for a vote.

In recent days, Republican senators had been under fire for their opposition to the legislation.

The House quickly passed the Senate bill a few hours later, as was widely expected. The vote was 206 to 60, breaking down largely along party lines. The White House said President Obama would sign the bill into law.

After the Senate vote, a celebration broke out in a room in the Capitol that was packed with emergency workers and 9/11 families, as well as the two senators from New York, Charles E. Schumer and Kirsten E. Gillibrand, and the two senators from New Jersey, Frank R. Lautenberg and Robert Menendez. The senators, all Democrats, were greeted with a huge ovation and repeated chants of “U.S.A.! U.S.A.!”

Mr. Schumer, the state’s senior senator, allowed Ms. Gillibrand to address the group first, in apparent deference to the role she took in the Senate on the 9/11 legislation.

“Our Christmas miracle has arrived,” she said to applause and cheers.

“To the firefighters here, the police officers here, everyone involved in the recovery, all the volunteers, the family members: Thank you!” she continued. “It was your work, it was your heroism, it was your dedication that made the difference. It was your effort, coming here week after week to tell senators and Congress members about your stories and what you went through.”

The votes came after prolonged aggressive lobbying by top New York officials and lawmakers, police and firefighter groups and 9/11 families, who argued that the nation had a moral obligation to provide medical assistance to rescue workers who spent days, weeks and even months at ground zero.

In a reminder of the bill’s long road to passage, Secretary of State Hillary Rodham Clinton, who sponsored the legislation when she represented New York in the Senate, was coincidentally at the Capitol on Wednesday for a Senate vote on ratification of the New Start treaty

The 9/11 health measure calls for providing $1.8 billion over the next five years to monitor and treat injuries stemming from exposure to toxic dust and debris at ground zero; New York City would pay 10 percent of these costs.

There are nearly 60,000 people enrolled in health-monitoring and treatment programs related to the 9/11 attack. The federal government currently provides the bulk of the financing for these programs.

The legislation adopted on Wednesday also sets aside $2.5 billion to reopen the September 11th Victim Compensation Fund for five years to provide payment for job and economic losses.

In a statement released by City Hall, Mayor Michael R. Bloomberg hailed the passage of the legislation, saying it “affirms our nation’s commitment to protecting those who protect us all.”

The bill was adopted during a flurry of activity as lawmakers rushed to adjourn for the year. It was a major turn of events since the bill appeared to have fallen victim to partisan squabbling and rancor.

In September, after years of negotiation and debate, the House passed legislation that called for providing $7.4 billion over eight years to cover the medical care of 9/11 rescue workers and others. But this month, Republicans derailed that legislation in the Senate, expressing concern about its cost.

By Wednesday, Senate Republicans budged, following a barrage of criticism over the last few days — not just from Democrats, but also from allies, including former Mayor Rudolph W. Giuliani of New York and conservative news outlets like Fox News. The 9/11 health care issue also became a cause of Jon Stewart, who used the platform of his program, “The Daily Show,” to bring national attention to the bill.

Before agreeing to lift their opposition, Senate Republicans managed to get Democrats to scale back the size of the original House bill.

The Senate adopted the legislation by a voice vote, eliminating the need for a recorded vote, as lawmakers rushed to bring the Congressional session to a close.

One of the main critics of the original House bill, Senator Tom Coburn, Republican of Oklahoma, expressed satisfaction with the legislation’s final cost.

“Every American recognizes the heroism of the 9/11 first responders,” Mr. Coburn said. “But it is not compassionate to help one group while robbing future generations of opportunity.”

Still, the acrimonious fight over the 9/11 legislation appeared to leave Republicans on the defensive and concerned that their party had been unfairly demonized for raising legitimate objections to the original $7.4 billion bill the House passed.

“Some have tried to portray this debate as a debate between those who support 9/11 workers and those who don’t,” said Senator Mitch McConnell of Kentucky, the Republican leader. “This is a gross distortion of the facts. There was never any doubt about supporting the first responders. It was about doing it right.”

In the House, there was some disappointment among Democrats over the deal cut in the Senate. But many concluded that the Senate bill was the best they could get at the moment.

“This compromise isn’t everything we wanted,” Representative Carolyn B. Maloney, Democrat of New York, a chief sponsor of the original legislation, said. “But in the end we got a strong program that will save lives.”

The bill is formally known as the James Zadroga 9/11 Health and Compensation Act, named after a New York police detective who took part in the rescue efforts at ground zero and later developed breathing complications. He died in January 2006. The cause of his death became a source of debate after the city’s medical examiner concluded that it was not directly related to the attack.

The legislation allows for money from the Victims’ Compensation Fund to be paid to any eligible claimant who receives a payment under the settlement of lawsuits that more than 10,000 rescue and cleanup workers recently reached with the city. Currently, those who receive a settlement are limited in how much compensation they can get from the fund.

In New York, a federal judge told lawyers for the 10,000 that payments from the settlement must start going out by late January. The judge, Alvin K. Hellerstein of United States District Court in Manhattan, worked out a timetable with the lawyers so that the settlement terms, which call for payments of at least $625 million, become final within the next two weeks.