The US House of Representatives passed a landmark health reform bill aimed at cutting costs and extending coverage to Americans who lack insurance.
The House vote late Saturday marked the biggest victory yet for President Barack Obama's top domestic priority and came after months of wrangling in Congress and fierce debates in the country.
The road is even tougher in the Senate, which has yet to start debating its own version of health-care legislation.
The bill passed by a 220-215 vote with 39 of Obama's own centre-left Democrats voting against it and one opposition Republican voting yes.
Obama visited Capitol Hill on Saturday to help prod members of his own party to support the legislation, which includes a controversial government-run insurance option. Some moderates among the House Democrats had sought concessions before voting with their own party.
There had been doubts until the last hours whether the vote would actually be taken on Saturday or postponed until Sunday or later.
The health-care overhaul has been the subject of a highly divisive debate for the past year. Democrats, who control both houses of Congress, are pushing for reforms aimed at bending the cost curve of the world's most expensive health-care system, which makes up about 16 percent of the economy.
Obama called Saturday's vote "historic", saying the bill "would finally make real the promise of quality, affordable health care for the American people".
"Now the United States Senate must follow suit and pass its version of the legislation," he said. "I am absolutely confident it will, and I look forward to signing comprehensive health insurance reform into law by the end of the year."
The House measure was projected to cost $894 billion over 10 years, but its backers claimed it would reduce the federal budget deficit by $104 billion. It would be paid for through efficiency measures and new taxes on the most expensive insurance plans, according to the non-partisan Congressional Budget Office.
The legislation would force Americans to buy health insurance and increase government subsidies for the poor. The Congressional Budget Office estimates are that the reforms would increase health-insurance coverage to about 96 percent of the US population, up from 83 per cent.
Recent endorsements from two major lobbying groups - the American Medical Association, an advocacy group for doctors, and AARP, which represents retirees - appeared key to completing the House push.
Republicans remained strongly opposed, arguing that the proposals amount to a government takeover of the largely private system.
The bill includes a government-run insurance option, which is favoured by left-wing Democrats but has been a lightning rod for criticism of health reform by conservatives and some moderate Democrats.
Politicians have failed for decades to agree on a comprehensive overhaul of the US health-care system. The last major reform was approved in the 1960s when Congress created two government-run insurance options: Medicare for seniors and Medicaid for the poor.