Washington ? Despite solid House approval, the idea of letting Americans buy prescription drugs from foreign suppliers at a fraction of the U.S. cost still faces a formidable hurdle in the Senate. Key senators in both parties argue that the safety risks may be too great.

Supporters of the House bill acknowledged the uncertain future of their legislation. But they said the strong 243-186 vote early Friday morning, in the face of opposition from the White House and GOP leaders and an intense lobbying effort by the pharmaceutical industry, was evidence of growing grass-roots demand for cheaper medicine.

Opening access to imported drugs, which can be half or even a 10th the cost of an identical product sold in America, could cost the pharmaceutical industry billions that it says it needs to research new treatments.

“I don’t know if we are going to win this fight,” said Rep. Dan Burton, R-Ind., a conservative who joined with some of the House’s most liberal Democrats in promoting the measure. But “last night we sent a very strong message” to the pharmaceutical industry that it is going to have to reevaluate the prices they charge American consumers.

The House bill, sponsored by Reps. Gil Gutknecht, R-Minn., Jo Ann Emerson, R-Mo., and Rahm Emanuel, D-Ill., orders the Health and Human Services Department to set up a system to allow importation of FDA-approved drugs from FDA-approved facilities in Canada, the European Union and seven other nations.

The measure also would require imported medicine to be shipped in anti-tampering and anti-counterfeiting packaging.

It goes well beyond language in a $400 billion measure to provide a prescription drug benefit to Medicare recipients now being crafted by House and Senate negotiators. Both the House and Senate Medicare bills would allow imports only from Canada and require the Health and Human Services Department to certify that the imports are safe.

Congress has twice before passed legislation dealing with drug importation, but both required HHS certification and HHS secretaries in both the Clinton and Bush administrations have refused to do so.

Thursday, 53 senators signed a letter opposing the bill on safety grounds.