At the same time, civil rights leaders were seeking to distance their movement from the same-sex marriage struggle and an Oregon community decided to back off from issuing marriage licenses until the courts intervene.
The constitutional amendment is sponsored by Rep. Wayne Allard (R-Colorado).
"We wanted to define marriage as a union between a man and a woman," he said.
Allard will testify, as will openly gay Rep. Barney Frank (D-Mass.) and an array of legal scholars, reports CBS News Capitol Hill Correspondent Bob Fuss.
President Bush has endorsed amending the constitution as the only sure way to stop courts from allowing same-sex marriages.
Supporters of the constitutional ban Monday unveiled a change in their proposal that they said would leave state legislatures with the unambiguous right to recognize civil unions.
"This new language makes the intent of the legislation even clearer," said Allard.
The deletion of five words did nothing to lessen the opposition of Democratic critics of the proposed constitutional amendment.
Amending the Constitution takes two-thirds of Congress and approval by three-fourths of the states. Most attempts fail, says Fuss, and those that succeed take years.
Meanwhile, more than two dozen black pastors added their voice to the critics of same-sex marriage, attempting to distance the civil rights struggle from the gay rights movement and defending marriage as a union between a man and a woman.
"When the homosexual compares himself to the black community, he doesn't know what suffering is," said the Rev. Clarence James, an African-American studies professor at Temple University.
Jones and 29 pastors rallied late Monday with their supporters at an Atlanta-area church where they signed a declaration outlining their beliefs on marriage and religion.
The declaration is meant to pressure state representatives to approve a constitutional ban on gay marriages, which will be considered again by the Georgia House as soon as this week.
The declaration says same-sex marriage is not a civil right, and marriage between a man and a woman is important because it's necessary for the upbringing of children.
"To equate a lifestyle choice to racism demeans the work of the entire civil rights movement," the statement said. "People are free in our nation to pursue relationships as they choose. To redefine marriage, however, to suit the preference of those choosing alternative lifestyles is wrong."
In Oregon, faced with the threat of a lawsuit, a county that had been poised to become the state's second to issue gay marriage licenses has now backed off until courts intervene.
Commissioners in Benton County, home to Oregon State University and the liberal city of Corvallis, decided Monday to stop issuing all marriage licenses until there is a court ruling on whether gay marriage is legal in Oregon.
Attorney General Hardy Myers sent Benton County commissioners a letter that the state was "well-positioned to initiate a lawsuit were they to proceed as proposed," said Kevin Neely, Myers' spokesman.
Benton County commissioners then later said they were "respecting the attorney general's request" by postponing the issuing of same-sex marriage licenses.
The county had been poised to follow Multnomah County, the state's most populous, which has issued over 2,400 licenses to gay couples since March 3.
Gay marriage advocates said they were disappointed.
"It's unfortunate that the attorney general put them in a position where they felt they had no choice but to stop issuing marriage licenses altogether," said Roey Thorpe, executive director of Basic Rights Oregon.
. 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 consideringthat would outlaw same-sex marriages.
While the majority of Americans oppose legalizing same-sex marriage, people younger than 30 have consistently been more supportive of it than their elders.
For instance, a poll taken last month for the National Annenberg Election Survey at the University of Pennsylvania showed that just over half of people ages 18 to 29 would oppose a law in their states that would allow lesbians and gay men to marry a same-sex partner. That compares with 61 percent of 30- to 44-year-olds; two-thirds of 45- to 64-year-olds; and 81 percent of those 65 and older.
The poll also found that fewer than half of those younger than 30 supported a federal constitutional amendment banning same-sex marriage.
The previous Constitutional ban 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. Two other minor changes in wording were made in the 45-word proposal.
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."