House Democrats passed historic legislation late Saturday to expand the nation's health-care system, securing 220 votes -- two more than needed -- with the support of one Republican lawmaker.

During a roll call vote, applause broke out in the House as the tally hit 218 -- a target Speaker Nancy Pelosi (D-Calif.) and other party leaders have been focused on for days.

The vote came after 12 hours of debate, first on procedural matters and, starting at 2 p.m., on the merits of the legislation, the centerpiece of President Obama's domestic policy agenda.

"The yeas are 220, the nays are 215," Pelosi announced at 11:15 p.m. "The bill is passed."

Both parties closely guarded their private whip counts in advance of the late-night vote on the entire package, but the public pronouncements by lawmakers during the day suggested an extremely tight vote.

Democrats had remained publicly optimistic they would come out just above the minimum 218 votes they need for victory. Freshman Reps. Dan Maffei (D-N.Y.) and Ann Kirkpatrick (D-Ariz.), joined by second-term Rep. Michael Arcuri (D-N.Y.), announced their support for the bill, giving a boost among the critical bloc of votes coming from the roughly 75 Democrats who were elected within the last three years. Rep. Jim Cooper (D-Tenn.), a veteran who is considered a health-care expert among conservative southerners, was also expected to vote for the legislation.

"We know the status quo is unacceptable and bankrupting individuals, businesses and all levels of government. While this bill is not perfect, it is necessary that we pass it so we can begin to fundamentally reform health care," Maffei said in a statement as debate inched along.

But Pelosi (D-Calif.) saw a wave of other Democrats, largely a collection of freshmen and those from southern districts, come out against the legislation. Shortly after 6 p.m., Democratic and GOP staffs had identified at least 30 "no" votes from the 258-member Democratic caucus.

"Health care costs are crippling our small businesses and forcing families into bankruptcy, and any reform plan needs to reduce those costs," Rep. Glenn Nye (D-Va.), a freshman from the Norfolk-based district, said in a statement announcing his vote.

Pelosi could afford to lose just nine more lawmakers from her caucus and still pull off a victory.

Debate began about 2 p.m., after House Democrats received a pep talk from President Obama and the House voted 242 to 192 to approve the rules of the health-care debate, a vote that officially permitted the chamber to proceed to the substantive merits of the legislation.

If debate continues on its current course, House Democrats may be hours away from approving a 1,990-page bill that would require individuals to buy health coverage and would create an individual insurance market to provide affordable policies for people who do not receive health benefits through their employers.

"I am absolutely confident that you guys will get this done. I am absolutely confident that when I sign this bill in the Rose Garden, each and every one of you will be able to look back and say, 'This was my finest moment in politics,' " Obama told Democrats during a 20-minute talk in the Cannon Caucus Room, according to the notes of one Democrat in attendance.

The president urged lawmakers to pass his landmark health-care initiative and warned that voting against the trillion-dollar measure would not inoculate them from Republican attacks next fall. Visiting House lawmakers for the first time in many months, Obama said the vote expected Saturday evening would be a historic moment, not just for the nation's health-care system but for their legislative careers.

Obama did not address specific issues that have come to a head in the final days of what has been a months-long debate, including a last-minute compromise to allow a controversial amendment on abortion, nor did he take questions from the Democrats. But the president recognized the political fear among dozens of anxious Democrats who faced heated anger from constituents during town-hall meetings over the August recess and who saw independent voters abandon Democratic candidates for governor in Virginia and New Jersey in Tuesday's elections, with exit polls showing those non-aligned voters were concerned about government spending and takeovers of private sector industries.

And he delivered a blunt warning to those wavering lawmakers, telling them that they face more political heat if the measure fails. "If you think the Republicans are not going to go after you if you vote no, think again," the president said, according to one attendee's notes.

Despite the late worries about the abortion dispute, some Democrats emerged more confident after the pep talk from Obama. "It was an inspirational speech," said Rep. Jan Schakowsky (D-Ill.), who is working to defeat the abortion vote later today but predicts the overall legislation will be approved. "I think we had the votes before the speech, and hopefully, we picked up a few more."

House leaders were increasingly confident that they have quelled the dispute.

"Today we will reform health care for America in the House of Representatives," House Majority Leader Steny Hoyer (D-Md.) said after emerging from the meeting with Obama.

Leading up to Saturday's debate, the fate of the trillion-dollar health plan hung on the outcome of negotiations with about two dozen anti-abortion Democrats, who sought to explicitly prohibit federal funds from paying for abortion through new, federally sponsored health-insurance plans. The U.S. Conference of Catholic Bishops, which backed the holdouts, circulated a letter late Friday arguing that the legislation could otherwise force individuals who oppose abortion to indirectly subsidize the procedure with their tax dollars.

House Democratic leaders agreed Friday night to settle the impasse by allowing the full House to vote on the proposed compromise, a risky decision that could jeopardize final passage if Democrats don't accept the outcome en masse. The plan satisfied the demands of Catholic bishops.

Leading up to the vote, speeches on the House floor split along predictable partisan lines. No Republicans are expected to support the bill.

"I just don't think it's right in the guise of helping Americans, to mandate what they have to do. I don't think it's right to mandate that they have health insurance or you might go to jail," said Rep. Joe Barton, (R-Tx). "I just don't think mandating to Americans is a good idea."

For Democrats, the debate represented a signal moment in a 100-year quest to provide universal health coverage. Although some individuals would be exempted from the mandate -- including about 12 million illegal immigrants -- the bill would effectively close the uninsured gap by a combination of new private insurance plans, a so-called "public option," and a vast expansion of Medicaid, the state-federal program that serves low-income people.

"This bill is deserving of the greatness of our nation," said Rep. James Moran (D-Va.).

In recent days, however, the bill's major provisions were pushed aside while Democrats haggled over abortion language. The large group of Democrats who support abortion rights said that they were willing to accept only limited revisions to the health-care package, and House leaders struggled to find a compromise that would pass muster with the party's abortion-rights wing while winning the blessing of the bishops.

By allowing a vote on the amendment by Rep. Bart Stupak (D-Mich.) and other anti-abortion lawmakers, House leaders achieved the latter goal: The Catholic church signed off on the late-night deal and issued a letter early Saturday saying it provide a critical endorsement of the health care package if the amendment is adopted.

"Passing this amendment allows the House to meet our criteria of preserving the existing protections against abortion funding in the new legislation," the Bishops wrote. "Most importantly, it will ensure that no government funds will be used for abortion or health plans which include abortion." But many pro-choice Democrats were not happy, and some were threatening to withhold their votes on final passage if the amendment is adopted.

"The goal of passing health care reform is a very strong one, so we'll see," said Rep. Lois Capps (D-Cal.)

Pelosi still has little margin for error: Democrats control 258 seats and need 218 votes for passage, meaning she can afford to lose only 40 members of her caucus. Obama, his top aides and at least two Cabinet secretaries worked the phones Friday, trying to win over wavering lawmakers. Asked if she had the votes for passage, Pelosi said only: "We'll see when we get to the floor."

A separate dispute over immigration policy also festered as debate began. Hispanic lawmakers said they had received assurances from House leaders that the bill would not be changed to bar undocumented workers from purchasing insurance through newly created insurance marketplaces, although those workers would be barred from receiving subsidized coverage of any kind. Language promoted by the White House and adopted by the Senate Finance Committee would establish such a barrier.

Hispanic lawmakers remained concerned, however, that Republicans would attempt a parliamentary maneuver to add the provision to the bill -- and that the maneuver would attract enough votes from conservative Democrats to win approval. Republican aides declined Friday to say whether they were planning such a move.

House leaders were working late Friday to secure assurances from about 20 Hispanic Democrats that they would vote for the health-care package regardless. Hispanic lawmakers, for their part, were seeking Pelosi's commitment to try to prevent Democratic defections. Leaving a meeting in the speaker's office Friday morning, Rep. Raul M. Grijalva (D-Ariz.) said: "We have the support of leadership to defeat that."

Other undecided lawmakers had more fundamental concerns about the health-care package. Rep. Jason Altmire, a second-term Democrat who represents a blue-collar district in suburban Pittsburgh, was the focus of an aggressive lobbying effort Friday, taking calls from Obama, Pelosi and White House Chief of Staff Rahm Emanuel, as well as Health and Human Services Secretary Kathleen Sebelius and Education Secretary Arne Duncan.

A former hospital association executive, Altmire said the White House was appealing to his firsthand knowledge of the insurmountable flaws in the current system, and encouraging him to use that expertise to explain the benefits of reform to his deeply skeptical constituents.

"They're pulling out all the stops," said Altmire, who opposes the bill's proposed surtax on the wealthy, among other provisions. "I don't think there would be this drama if they had the votes."

For others, the lobbying campaign was working. Rep. Jared Polis of Colorado, who voted against the package in the Education and Labor Committee, threw his support behind the measure Friday, largely because House leaders had adjusted the surtax to apply only to family income over $1 million, rather than the $350,000 threshold set earlier. The new version, Polis said, has "become a much more favorable bill for small business."

Amid the frenzied horse trading, the hard "no" votes wandered the ornate halls of the Capitol serenely unaccosted. Democratic Rep. Artur Davis, who is running for governor of Alabama and thinks the bill costs too much, lingered outside the House chamber, leisurely chatting on a cell phone. Rep. Charlie Melancon (D-La.), who is also running statewide and voted against the House package in the Energy and Commerce Committee, cheerfully complained to reporters that he was "feeling neglected."

The "no" votes, who numbered around 25, gained at least one member Friday: Maryland Rep. Frank M. Kratovil Jr., a freshman Democrat who represents the traditionally Republican Eastern Shore. After reading the revised package House leaders unveiled last week, Kratovil said the bill is better than it was in July, but it still costs too much and would impose too heavy a burden on small businesses, many of which would be required for the first time to offer health insurance to their workers or face a stiff fine.

Kratovil said he had not received any calls from the White House. But "at this point," he said, "there's not much point in lobbying me."