Rejecting a plea from President Bush, the Senate has scuttled a measure banning gay marriage as an amendment to the US Constitution. The vote was 50-to-48, ten short of the 60 needed to keep the measure alive. Republican Rick Santorum had said preserving traditional marriage was the ultimate form of "homeland security." But Democrat Tom Daschle said there was no "urgent need" for a constitutional amendment. Supporters conceded in advance they didn't have the votes to pass the measure, but vow to keep the issue alive.