WASHINGTON — Pressed hard by Gulf state governors, senators from both political parties warned the White House yesterday to drop its opposition to a proposed expansion of Medicaid for Hurricane Katrina evacuees and devastated states — or face a potentially embarrassing political rout.

President Bush has found himself at odds with members of his party over how best to deliver health care to impoverished hurricane victims. Senate Finance Committee Chairman Charles Grassley, R-Iowa, and Montana Sen. Max Baucus, the panel's ranking Democrat, have proposed a five-month expansion of Medicaid to cover not only those evacuees previously entitled to federal health insurance — mainly women and children — but also poor, childless men.

The legislation — totaling nearly $9 billion — also would establish an $800 million fund for health-care providers treating poor evacuees, and it would allow the federal government to pick up costs that otherwise would be assumed by the affected states.

The Louisiana Department of Health and Hospitals has found that one-fifth of evacuees applying for Medicaid have been ruled ineligible even before they could finish their paperwork. Of those who do apply, one-third are being turned away, almost always because they do not fit fixed Medicaid eligibility categories.

The administration has balked at expanding the program, asserting that health care can be provided more efficiently and less expensively by granting waivers of Medicaid rules to states that have accepted evacuees. In a letter to Senate leaders, Health and Human Services Secretary Mike Leavitt called the legislation "a new Medicaid entitlement for Katrina survivors" and "a massive new federal program."

But with the governors of Louisiana, Mississippi and Alabama all demanding legislative action before the Senate Finance Committee, panel members said they were ready to move forward, with or without the president.

"I'm prepared to be hard-nosed, too, at some point. At some point, you have to tell them: 'OK, ante up and kick in or get out of the game,' " Sen. Trent Lott, R-Miss., warned the White House. "But I'm not looking for a fight. I'm looking for help, for people that are desperate."

Grassley said other, far-more-costly solutions also are being proposed that the Senate could pass easily. And, he said, the $35 billion in entitlement spending cuts over the next five years that Bush wants badly will have no chance of passage if Medicaid relief cannot be approved now.

The fight over the bill exemplifies the Republican dilemma in the wake of hurricanes Katrina and Rita. Members of both parties have been quick to open the Treasury to help hurricane victims and show a new sensitivity to the plight of the poor. But conservatives in the House and the Senate are complaining loudly about the surge in spending amid lingering budget deficits.

The Senate had expected to pass the Medicaid legislation Monday night by a procedural voice vote, which would have required unanimous support. But pushed by the White House, a handful of Republicans objected.

Supporters of the bill had the megaphone yesterday. Mississippi Gov. Haley Barbour, a Republican, questioned the expansion of Medicaid eligibility rules but said the legislation's provision allowing the federal government to assume 100 percent of the expanded health-care costs is "just crucial." Louisiana Gov. Kathleen Blanco, a Democrat, pleaded for immediate legislative action.

"Does this mean it's going to be permanent? Does this mean it's going to be long-term? Absolutely not," said Alabama Gov. Bob Riley, a Republican. "But during this critical time right now ... we have to take care of some of the people suffering."

Under the waiver process, Medicaid bills incurred by evacuees in other states would be sent to their home states in the Gulf, according to a letter from Grassley and Baucus to Leavitt. Without new legislation, the administration will have no choice but to expect Louisiana and Mississippi to pay their share.