The Vermont Senate on Tuesday rejected a constitutional amendment that would define marriage as a union between one man and one woman.

The amendment was proposed by opponents of Vermont's groundbreaking legislation that would give homosexual couples rights and benefits similar to marriage.

The senators voted against the measure 17-13, seven votes shy of the required two-thirds majority.

"It's unnecessary and redundant," Senate Judiciary Committee Chairman Richard Sears said.

As spectators thronged the small chamber, the Senate then took up a separate constitutional amendment that would overturn the state Supreme Court's December ruling that gays and lesbians are being unconstitutionally denied the rights and benefits of marriage.

Even before the debate opened, supporters and opponents in the 30-member Senate predicted the two proposed constitutional amendments would fail to garner the two-thirds majority required for them to be forwarded to the House.

"Many of my constituents said 'we want a vote, we want a say in this issue,"' Sears said. "Fortunately or unfortunately, depending on your position, Vermont does not have a referendum government. I do not believe, personally, that the Constitution and amendments thereto should be used as a means of substitution for the referendum form of government."

After considering the two amendments, the Senate will turn to the civil unions bill that was rewritten by the Judiciary Committee. That bill is strikingly similar to the one passed last month in the House, so there has been pressure on senators to simply pass the same language to avoid another close vote in the House. The bill passed the House 76-69. There are no comparable civil union laws on the books anywhere else in the country.

Senate leaders predicted Monday, however, that the Judiciary Committee's version of the bill would pass, setting up another House vote.

"I think, given the natural concerns around this issue, it wouldn't look too good to look like a rubber stamp," said Sen. Jeb Spaulding.

The biggest difference in the two measures is when the first civil unions could be formed. The House set the effective date as Sept. 1. The Senate committee moved the effective day up to July 1.

Civil unions would require the state to grant to same-sex couples all the benefits of marriage given to opposite-sex couples, including making medical decisions for one another, certain tax breaks and inheritance rights.