WASHINGTON — The Senate moved yesterday toward opening the way for Americans to import prescription drugs from Canada, seeking to ease a ban on cheaper medicine crossing the border.

The proposal, which was approved 68–32, would create a Canadian loophole in a Food and Drug Administration ban on importing prescription medicine into America. It was offered as part of a $31.7 billion Homeland Security Department spending blueprint for the fiscal year that begins October 1.

The department’s Customs and Border Protection bureau began aggressively seizing Tamiflu, Viagra, and other incoming medications at borders in November. Prescription drugs — even those manufactured in America — are generally sold at cheaper prices in Canada.

“We should demand that (Customs and Border Protection) focus on the true priority that we face on the war on terror,” said Senator Vitter, a Republican of Louisiana, of efforts to secure American borders. “Stripping small amounts of prescription drugs from the hands of seniors. … that should not be a priority.”

Mr. Vitter’s plan, which was embraced by Democrats, specifically would prohibit Customs and Border Protection from stopping people with doctors’ prescriptions for FDA-approved drugs from bringing the medicine into this country from Canada.

But Republican leaders vociferously opposed the plan for fear, they said, the drugs could be unsafe for consumers — or even present a terror risk.

Senator Gregg, a Republican of New Hampshire,said the proposal was an attempt to push the FDA into reversing itself while “creating a massive hole on our capacity to secure our borders and protect ourselves.”

“If I were a creative terrorist, I would say to myself, ‘Hey, listen, all I’ve got to do is produce a can here that says ‘Lipitor’ on it, make it look like the original Lipitor bottle, which isn’t too hard to do, fill it with anthrax,” Mr. Gregg said. Lipitor is a cholesterol-lowering drug.

Aides said the drug import plan was likely to be stripped out of the legislation — as it has been in past years — whenever it got to a conference of House and Senate lawmakers who will negotiate the final version. The administration also has opposed efforts to loosen the restrictions.

Two House spending bills this year — to fund the Homeland Security and Agriculture departments in 2007 — include the drug importation plan, said Kirstin Brost, spokeswoman for Rep. David Obey of Wisconsin, the top Democrat on the House Appropriations Committee.

The House has approved efforts to import drugs in six spending bills over the past seven years, Ms. Brost said, but the idea so far has survived the conference only once. In that year, 2000, the plan was eventually dropped because it was written in a way that couldn’t be carried out, Ms. Brost said.

While importing drugs into America is illegal, the FDA generally has not stopped small amounts purchased for personal use. Still, the FDA says it cannot guarantee the safety of imported drugs.