Nancy Pelosi, the speaker of the U.S. House of Representatives, presented a Democratic health-care bill Thursday that would extend medical coverage to about 36 million Americans.

"This an historic moment for our nation and families," Pelosi said, standing with other Democrats on the steps of Congress. "For nearly a century, leaders of every party and political philosophy have fought for health insurance reform.”

The latest proposal includes a government-run insurance plan that would be based on negotiated payment rates, instead of government-stipulated rates.

The proposal, as it stands, would cost about $894 billion US. Pelosi said the bill meets President Barack Obama's criteria of keeping the cost under $900 billion US over 10 years.

The bill would extend health coverage to millions more Americans, prevent insurance companies from denying coverage based on pre-existing medical conditions and require employers to offer coverage to their staff.

Congressional officials said the bill would extend coverage to 96 per cent of Americans.

Obama said Thursday he was pleased that the House bill includes the public option.

Democrats in the Senate are hoping to get their own health-care bill passed by the end of the year. The Senate version unveiled by Majority Leader Harry Reid earlier this week would allow states to opt out of the government-run plan. That is an option not included in the House version.

The bill is the result of months of negotiations between liberal and moderate Democrats. It is watered down from earlier proposals in a bid to win the support of moderate Republican Party lawmakers.

The Republican response was to pan the Democrats' 1,990-page plan, claiming it amounted to a government takeover of the health-care system.

"It will raise the cost of Americans' health insurance premiums, it will kill jobs with tax hikes and new mandates, and it will cut seniors' Medicare benefits," said Republican House Leader John Boehner of Ohio.

The Republicans have vowed to make health-care reform a key issue in next year's elections, when all 435 seats in the House are up for grabs.