Southern Democrats' opposition to gay marriage (search) is an early signal that this hot-button issue may supersede party politics.

On Thursday, rural white Democrats joined with Republicans of all stripes to back an amendment to Georgia's state constitution banning gay marriage. After hours of impassioned debate, the measure fell three votes short, 117-50, of the two-thirds majority it needed to pass the 180-member Democrat-run statehouse.

The vote was an early test of support in the states for President Bush's push for an amendment to the U.S. Constitution. In conservative Georgia, the Democratic party was almost evenly split, with 49 voting no, 47 voting yes and 12 not voting. The party was split largely along demographic lines, with blacks and urban whites voting against the measure and rural whites supporting it.

Supporters vowed to push for a new vote in the House on Monday, with activists on both sides promising a fight.

In addition to Southern Democrats, such groups as Catholic Democrats, gay Republicans and constitutional conservatives may throw curves in the debate over whether couples of the same sex should be allowed to wed.

Social issues have long divided both parties, and on matters related to homosexuals, regional and religious differences cause the issue to be more complicated than a mere party-line fight.

"There's no question" that this issue "transcends party politics" for Catholics, said William Donohue, president of the Catholic League (search).

He said that Catholics are almost evenly split between the two parties, but that opposition to gay marriage is an important value for all Catholics.

Catholic Democrats will be one of the key groups to watch, said American Enterprise Institute (search) Research Associate John Fortier. "Look at the Massachusetts debate, which will divide different factions of the Democratic Party."

Gay Republicans form another constituency that will not use party loyalty to determine how to deal with this issue. The Log Cabin Republicans (search) vowed to fight the amendment effort and said it would be a contentious issue within the GOP.

"Pandering to the radical right will alienate the centrist, fair-minded swing voters who will ultimately decide the winner of what promises to be a close presidential election. Following the same failed path of 1992, we hear the echoes of Pat Buchanan that helped lead to the defeat of the first President Bush," the nation's largest gay Republican group said in a statement.

Some moderate Republicans are wary about wading into social conservatism. Among those who have already voiced skepticism about the proposed amendment Rep. Deborah Pryce of Ohio, Rep. Amo Houghton of New York and Rep. David Dreier of California.

Even major Bush backers like House Majority Leader Tom DeLay of Texas and Senate Majority Leader Bill Frist of Tennessee, said there would be no quick action on Capitol Hill.

Although Bush's initiative is expected to appeal to his socially conservative base, it could alienate constitutional conservatives, individuals who are skeptical about making changes to the Constitution. In an effort to highlight this division, gay rights group Human Rights Campaign (search) and libertarian organization Citizen Outreach (search) ran a radio ad campaign last month that featured prominent conservatives opposed to an amendment.

"Think it's conservative to amend the Constitution to ban marriage for gay and lesbian couples? Plenty of conservatives across American don't," the ads say.

"They believe that, even if you oppose gay marriage, you don't amend the Constitution to deal with every controversial social issue. And you definitely don't amend the Constitution to give more power to the federal government," the commercial continues.

"It's why conservative former Wyoming Senator Alan Simpson says the constitutional amendment 'minimizes the Constitution.' Conservative columnist George Will calls the Federal Marriage Amendment (search) 'a misuse of fundamental law.' And conservative former Congressman Bob Barr — the man who wrote the Defense of Marriage Act (search) — calls a Constitutional Amendment 'needlessly intrusive and punitive.'"

Chuck Muth, president of Citizen Outreach (search), said the goal of the campaign was to reach out to conservatives, urge them to return to their states rights roots and encourage them to leave the Constitution alone.

Throwing cold water on the notion that significant constituencies would buck the party line, Larry Sabato, director of the University of Virginia's Center for Politics (search), said, "It certainly is" a partisan issue.

"There are always exceptions in both parties, but the vast majority of Democrats favor either gay marriages or civil union and the vast majority of Republicans oppose. The exception is some of the Republicans in the northeast favor civil unions; very few favor gay marriage. And a few of the Democrats from southern states and other conservative areas are opposed, but by and large there is a clear partisan divide on this issue," Sabato said.