Democrats also took issue with Allard and Musgrave for rewording the proposed amendment on the eve of Tuesday's hearing. The authors defended their changes as technical.
The new text reads: "Marriage in the United States shall consist only of the union of a man and a woman. Neither this Constitution, nor the constitution of any state, shall be construed to require that marriage or the legal incidents thereof be conferred upon any union other than the union of a man and a woman."
The sponsors deleted language that would have required that the amendment be ratified by three-quarters of the states within seven years.
In the second sentence, they also deleted the phrase "nor state or federal law," which had followed the words, "Neither this Constitution, nor the constitution of any state."
The sponsors said the changes were meant to ensure that state legislatures could enact civil-union laws and grant benefits to domestic partners if they chose to do so.
Although Allard insisted that the amendment, as worded, would not affect "adversely any state's effort to deal with the issue of civil unions," he indicated that he was open to changes.
Whatever text is ultimately adopted by the committee, both Republicans and Democrats say the chances of Congress passing any marriage amendment in this election year are slim.
A vote of two-thirds of each chamber of Congress is required to pass a constitutional amendment, which must then be ratified by the legislatures of three-fourths of the states before it can become law. Neither the House nor the Senate has set a date for the proposed amendment to come to a vote.
Senate Minority Leader Tom Daschle (D-S.D.) dismissed the whole exercise Tuesday as politically motivated.
"We're not even close to having votes sufficient to pass a constitutional amendment," Daschle told reporters.
The measure has been criticized not only by many Democrats, but by some Republicans, who argued that marriage laws are best left to the states, or are reluctant to amend the Constitution on a social issue.
But President Bush has publicly endorsed a constitutional amendment, although he has not specifically endorsed the Musgrave and Allard wording. Republicans have said the issue -- which is important to many social conservatives -- will play a prominent role in the presidential election campaign.
Sen. John F. Kerry of Massachusetts, the presumed Democratic presidential nominee, has said he is opposed to a constitutional amendment banning gay marriage.
Supporters of a constitutional amendment say that the Massachusetts Supreme Judicial Court forced them to act when it ruled last year that the state Legislature must recognize gay marriages.
"The only way to save laws deemed unconstitutional by activist judges is a constitutional amendment," Cornyn said.
Times staff writer Richard Simon contributed to this report.
