The historical health care legislation will be passed in the House on Saturday, predicted the second-ranking Democrat in the House of Representatives. The bill is aimed at extending coverage to tens of millions of uninsured Americans and banning the medical insurance industry from turning people away.

Representative Steny Hoyer told reporters House leaders would have the 218 votes needed to pass the sweeping bill that President Barack Obama has made the defining social goal of his young administration, presuming a couple of final issues are resolved. Hoyer acknowledged that the vote could be tight. ``I wouldn't refer to it as a squeaker, but I think it's going to be close,'' Hoyer said. ``This is a huge undertaking.''

Passage by the House would be a major step toward fashioning a bill to present to Obama to sign into law. Subsequent moves are likely to be substantially more difficult. The Senate, sharply divided on what the bill should look like, still must act, and differences between the two bills must be reconciled into a single document.

The Senate timeline appears likely to spill into next year, which would pose difficulties for the Obama administration because the issue could get caught up in election-year politics. Outside the Capitol, thousands of conservatives rallied Thursday against the Democrats' health care overhaul plan.

Protesters chanted, ``Kill the bill,'' as they awaited speeches by Republican leaders on Thursday. The campaign-style event kicked off a daylong Republican protest against the legislation. The protesters carried signs saying 'Vote no to government-run health care.''

The United States is the only developed nation that does not have a comprehensive national health care plan for all its citizens. Conservatives oppose increased government involvement as the first step on a slippery slope to ``socialized'' medicine, a term they use to denigrate other countries' health care systems, and insist on rugged American individualism, in which people should be responsible for their own health care. In addition, millions of Americans get health care from their employers and are reluctant to see any tinkering with that system.

Obama planned a rare visit to the House to persuade wavering Democrats. It had been set for Friday morning but after the fatal shootings at Fort Hood, Texas, the White House rescheduled it until Saturday.

A further boost was that The American Medical Association (AMA) and AARP, bodies representing doctors and seniors, endorsed the Bill on Thursday. The American Cancer Society also announced its support for the legislation. Support from the AARP proved a crucial stamp of approval when then President George W. Bush pushed the Medicare prescription drug benefit through a closely divided Congress in 2003.

With no Republican backing, Democrats will need overwhelming support from within their own caucus. An intraparty disagreement over how to prevent federal funds from being used to pay for abortion has not yet been entirely resolved, though Hoyer said that language being circulated by one anti-abortion Democrat seemed likely to be the basis for an agreement.