WASHINGTON — After months of struggle, House Democrats rolled out sweeping legislation today to extend health care coverage to millions who lack it and create a new option of government-run insurance.

A vote is likely next week on the plan largely tailored to President Barack Obama's liking.

House Speaker Nancy Pelosi said Congress was at a "historic moment."

Officials said the measure, once fully phased-in over several years, would extend coverage to 96 percent of Americans. Its principal mechanism for the wider coverage is creation of a new government-regulated insurance "exchange" through which private companies would sell policies in competition with the government.

Federal subsidies would be available to millions of lower-income individuals and families to help them afford the policies, and to small businesses as an incentive to offer coverage to their workers.

Large firms would be required to cover their workers, and most individuals would be required to carry insurance.