Supporters of a constitutional amendment to ban same-sex marriages were 10 votes short Wednesday as the U.S. Senate scuttled the proposal.

The vote came after President Bush urged Congress last February to approve an amendment tostop judges from changing the definition of the "most enduring human institution."

Presidential candidate Sen. John Kerry of Massachusetts and his running mate Sen. John Edwards of North Carolina both opposed the proposed amendment, but neither was present for the vote Wednesday.

After the defeat, Sen. John Cornyn, R-Texas, said the issue won’t go away.

“This is an important debate and one that is just beginning,” Cornyn said in a prepared statement.

“The assault on traditional marriage is not going away, and I hope that Congress will act to protect the most fundamental building block of our society.”

“This is a national problem,” Cornyn said, “and it requires a national response. Marriage is worth it; marriage is important enough to warrant the full legal protection of our laws.”

Democratic minority leader Sen. Tom Daschle, D-South Dakota, said there was no “urgent need” for a constitutional amendment. He said most states already have bans in place.

“Marriage is a sacred union between men and women. That is what the vast majority of Americans believe. It's what virtually all South Dakotans believe. It's what I believe,” he said.

In South Dakota, we've never had a single same sex marriage and we won't have any," he said. "It's prohibited by South Dakota law as it is now in 38 other states. There is no confusion. There is no ambiguity."

An Associated Press-Ipsos poll in March showed about four in 10 support a constitutional amendment to ban gay marriage, and half oppose it.