On the eve of the House debate on how much federal protection to offer patients in HMOs, Republican leaders signaled for the first time yesterday that they are willing to allow Americans a limited right to sue health plans that deny them the care they want.

The surprise announcement by House Speaker J. Dennis Hastert (R-Ill.) and several of his top lieutenants reverses the GOP's longstanding opposition to opening managed-care health plans to consumer litigation. It reflects a last-minute effort by the House leaders to ward off more sweeping "patients' rights" legislation by espousing a less onerous alternative.

Yet as the House begins its long-awaited debate on rival patient-protection plans today, it remains uncertain whether the Republicans' new tack will succeed. At least two dozen party dissidents appear poised to vote with a solid phalanx of Democrats for a bipartisan bill that would grant Americans far more latitude to sue their health plans, along with a somewhat broader set of additional guarantees.

Leading Republicans privately acknowledged yesterday that the broader bill they fear, sponsored by Reps. Charles Whitlow Norwood (R-Ga.) and John D. Dingell (D-Mich.) and favored by the White House, could well win by the end of the two-day debate. "This is not rocket science," one key Republican said. "You just have to look at how many co-sponsors they've got."

The final jockeying over strategy -- combined with a round of barbs exchanged yesterday by Hastert and President Clinton -- highlights the considerable political stakes for both parties in their handling of patients' rights. With elections looming next year, polls show that managed care has provoked widespread antipathy among American voters, while business groups believe it has helped control medical costs.

"There's no question this is one of the most important issues facing Congress," said Nelson Litterst of the National Federation of Independent Business, which opposes most of the regulations Congress is considering. Litterst and other lobbyists jammed a basement hallway of the Capitol, a few feet from where Hastert and other GOP members were privately discussing their new strategy.

Passage of either the Norwood-Dingell legislation or the bill that the speaker and his allies have now endorsed, introduced by Reps. Tom Coburn (R-Okla.) and John Shadegg (R-Ariz.), would go significantly beyond the steps taken by the Senate, which approved a GOP patients' rights bill in July. The Senate did not expand patients' ability to sue health plans, and many of the protections it adopted would help only about one-third of the 161 million Americans with private health insurance.

Both House measures also provide somewhat stronger protections than a patients' rights bill narrowly approved by the chamber a year ago, when the issue died in the Senate.

The partisan sparks generated by the issue come even though the three main bills before the House, including the most conservative one sponsored by Rep. John A. Boehner (R-Ohio), overlap more than they differ. Each, for example, would require HMOs to pay more emergency room bills, make it easier for women and children to visit obstetrician-gynecologists and pediatricians, and guarantee patients information about their health plans' rules. All three also would create grievance systems that would allow patients to protest to an independent body with clout if they think they have received inadequate care.

The central point of contention revolves around how far the government should go to help patients enforce their rights. The Norwood-Dingell bill would let patients file suit in state court if they were denied treatment that they think they needed, even if it was not covered under an HMO's benefits. Boehner's bill would not expand patients' ability to sue at all.

Coburn and Shadegg's approach seeks a middle ground, allowing patients to sue only in federal court, only for limited damages and only in instances when an independent appeals panel already has decided that an HMO improperly denied someone care.

Before considering which version is best, lawmakers today first will consider a related bill that would create a variety of tax incentives designed to widen access to health care by making insurance more affordable to individuals and small businesses. The most controversial of those incentives, supported by the GOP but vigorously opposed by Democrats, would allow more Americans to set up tax-free savings accounts to pay their medical bills.

Already, some Republicans appeared yesterday to be subtly trying to position themselves for a potential loss on the issue. The GOP began to suggest that lobbyists from the insurance industry and American business, who have sided with them in opposing lawsuits against HMOs, had not spoken out early or loudly enough against the Norwood-Dingell bill.

"They know this has been coming for a long time, and if they really wanted to defeat it they could have put their money where their mouth was and created a coalition, and beat the hell out of any member of Congress who was contemplating voting for the bills that would hurt them," said one Republican aide, who asked not to be identified.

Republicans broached that argument despite the fact that an alliance of business and insurance interests has spent millions of dollars in advertising to try to defeat the bill.

Even as fellow Republicans began criticizing the industry, Hastert was at a $1,000-a-plate fundraising breakfast attended by 17 health care lobbyists, including insurance representatives, organized by Deborah Steelman, a Washington health care consultant who is an adviser on health policy to GOP presidential candidate George W. Bush.

The White House yesterday seized on the event as fresh ammunition to criticize the GOP approach to patients' rights. "I'd like to ask them about sitting down with America's families instead," Clinton said.

Hastert jabbed back, issuing a statement that reiterated the GOP argument that the HMO litigation that Democrats support would create business for lawyers while making health care less affordable. "Mr. President," Hastert said, "I hope you will say no to helping trial lawyers, and say yes to helping the 44 million Americans who want health-care coverage."

Staff writer Helen Dewar contributed to this report.