Congressional supporters of a constitutional ban on gay marriage unveiled a change in their proposal Monday that they said would leave state legislatures with the unambiguous right to recognize civil unions (search).

The deletion of five words did nothing to lessen the opposition of Democratic critics of the proposed constitutional amendment (search). They responded by seeking an indefinite delay in a hearing set for Tuesday.

"This new language makes the intent of the legislation even clearer," said Sen. Wayne Allard, R-Colo., the amendment's leading advocate in the Senate. "To protect marriage in this country as the union between a man and a woman, and to reinforce the authority of state legislatures to determine benefits issues related to civil unions or domestic partnerships."

In response, one gay rights advocate questioned Allard's contention about what the change would mean, and Democrats on the Judiciary Committee seized on the change to request a postponement in the second of two Senate hearings.

Constitutional amendments to ban gay marriage have been introduced in the past in Congress without coming to a vote.

The issue has gained election-year urgency, though, in the wake of a court ruling in Massachusetts, a highly publicized spate of same-sex marriages (search) in San Francisco and elsewhere, and a request by President Bush that Congress vote on the issue.

Polls consistently show the public opposes gay marriage. But the division of opinion is far closer on the question of a constitutional ban.

Even so, Republican strategists have said they are eager to require Senate Democrats - including John Kerry, the party's presidential nominee-in-waiting - to vote publicly on the issue.

Kerry's home state has played a central role in the political drama on gay marriage in recent months with a ruling by the state's highest court that the Massachusetts constitution guarantees gay couples the right to marry.

In response, the Massachusetts Legislature has been considering proposed amendments to the state constitution that would outlaw same-sex marriages.

In Congress, Republican officials say the Senate Judiciary Committee is on track to vote on the proposed amendment to the U.S. Constitution in the second half of April.

Allard and Colorado GOP Rep. Marilyn Musgrave, the leading supporter of the amendment in the House, outlined their change at a news conference. The previous proposal said that neither the U.S. nor any state constitution or any state or federal law "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 revised proposal deletes the reference to state and federal laws.

In response, White House spokesman Trent Duffy said that the revision "actually brings it closer to the president's principles."

Stephanie Cutter, a spokeswoman for Kerry, said the Massachusetts senator is opposed to a constitutional amendment. "He believes the president is using it as a wedge issue to divide the nation when more important things are facing the American people."

As a result of the change, Allard said, the revised proposal would allow state legislatures to decide whether to recognize civil unions or domestic partnerships. Legislatures also could decide whether same-sex relationships would qualify for benefits associated with marriage, he said. Other officials added that the measure would continue to bar state or federal courts from issuing rulings that declare those rights to be inherent in either the U.S. Constitution or state constitutions.

Winnie Stachelberg, political director of the Human Rights Campaign (search), said Vermont's civil union law stemmed from a state law passed in relation to a state court ruling. "It's not quite clear what their change attempts to address and what it's actual impact would be," she said.