Updated

House Republicans tentatively agreed Thursday to relax a ban on importing prescription drugs from Canada, a controversial pre-election victory for lawmakers seeking to provide cheaper medication for elderly voters.

The deal would let Americans carry up to a 90-day supply of medication back to the U.S. from Canada without being stopped by Customs agents, House and Senate Republicans said.

"This is a very significant breakthrough," said Sen. David Vitter, R-La., who led the fight in the Senate to prohibit the Homeland Security Department from seizing prescription drugs being carried over the border.

The agreement "proves that we have significant majorities in favor of reimporting," Vitter said. "This really breaks the dam, and it shows that it's only a matter of time before we pass a full-blown reimportation bill."