WASHINGTON - House Democrats in the U.S. are poised to unveil health care legislation that would vastly alter America's medical landscape, requiring virtually universal sign-ups and offering a new government-run plan for people without affordable coverage.

House Speaker Nancy Pelosi was making plans to release the bill Thursday morning, contingent on the outcome of a meeting of House leaders Wednesday afternoon, according to lawmakers and aides.

The rollout would cap months of arduous negotiations to bridge differences between liberal and moderate Democrats and blend health care overhaul bills passed by three separate committees over the summer. The developments in the House came as Senate Majority Leader Harry Reid tried to round up support among moderate Democrats for his bill, which includes a modified government insurance option that states could opt out of.

The final product in the House, reflecting many of President Barack Obama's priorities, includes new requirements for employers to offer insurance to their workers or face penalties, fines on Americans who don't purchase coverage and subsidies to help lower-income people do so. Insurance companies would face new prohibitions against charging much more to older people or denying coverage to people with health conditions.

The price tag, topping $1 trillion over 10 years, would be paid for by taxing high-income people and cutting some $500 billion in payments to Medicare providers.

"I'm pretty confident that we've got the right pieces in place," said Rep. George Miller, D-Calif., chairman of the Education and Labor Committee, one of the three panels involved in writing the bill. "We can quibble over parts of it, but the fact is when you're taking a 60-year-old system that grew up in a rather haphazard fashion and you're trying to bring some coherence to it, these are sort of the things you have to do at the beginning of that process."

In the end, Pelosi, D-Calif., and other House leaders were unable to round up the necessary votes for their preferred version of the government insurance plan -- one that would base payment rates to providers on rates paid by Medicare. Instead, the health and human services secretary would be allowed to negotiate rates with providers and the program would be optional for states, the approach preferred by moderates and the one that will be featured in the Senate's version.