The U. S. Supreme Court will hear arguments on the legality of same-sex marriage this week as a rising tide of public opinion in favor of the practice is reshaping the political landscape.

From President Barack Obama’s flip to support gay marriage last year to the first ballot-box victories for same-sex marriage in November to the Republican Party rethinking its gay rights positions, same-sex marriage is gathering political momentum. But it is legal in only a handful of states and popular mostly among younger and more liberal voters, while the bulk of the Republican base remains firmly opposed.

The Court will hear separate cases regarding the constitutionality of California’s law banning same-sex marriage and the federal Defense of Marriage Act, which defines marriage as between one man and one woman. If the justices strike down the California law, it could imperil Georgia’s same-sex marriage ban approved by voters in 2004.

Pew Research Center wrote last week that the “rise in support for same-sex marriage over the past decade is among the largest changes in opinion on any policy issue over this time period.” Pew found support outweighing opposition to same-sex marriage for the first time in 2011. Its most recent national poll found 49 percent in favor with 44 percent opposed and those born after 1980 giving 70 percent support.

A Washington Post/ABC poll last week showed 58 percent saying gay marriage should be legal with 36 percent saying it should be illegal, with 81 percent of respondents younger than 30 approving. (The legal/illegal question wording consistently produces higher support than a support/oppose question.)

As with most issues, there is a regional and a red state-blue state split, said Jocelyn Kiley, a senior researcher at Pew. A Pew report in November found that the South Atlantic states (Georgia, Florida, North Carolina, South Carolina, Virginia and West Virginia) opposed gay marriage by 48 percent to 42 percent.

There has been little public polling in Georgia on the issue, but opposition appears to persist. A Landmark Communications/Rosetta Stone poll last May – around Obama’s announcement that he had changed his mind to support same-sex marriage – showed 27 percent of Georgians supported changing the law to legalize same-sex marriage, while 59 percent opposed.

A generational shift

Stanford University sociology professor Michael Rosenfeld said the public opinion shift has come more from younger people replacing older ones than people changing their minds.

For younger people “even if they think they would be uncomfortable if their own children were gay, there’s a certain degree of tolerance for what other adults would do in the privacy of their own home,” Rosenfeld said. “There’s an increasing degree of comfort with gay rights in general because they’ve been exposed to it.”

Pew’s most recent survey found that 14 percent of respondents had changed from opposing same-sex marriage to supporting it, while the rest said they always had supported it.

Rosenfeld said one exception is that African American and Latino support for same-sex marriage accelerated last year after Obama announced his shift.

In November, Maryland, Maine and Washington state became the first states to to legalize same-sex marriage through a vote, while a constitutional amendment defining marriage as between a man and a woman was defeated in Minnesota. Same-sex marriage also is legal in Connecticut, Iowa, Massachusetts, New Hampshire, New York, Vermont and the District of Columbia through judicial decisions and state legislative actions.

Politicians have responded to the rising tide. When Hillary Rodham Clinton announced her support for same-sex marriage last week, it was seen as a basic pre-requisite for her to run for president in 2016. Other potential Democratic presidential hopefuls, New York Gov. Andrew Cuomo and Maryland Gov. Martin O’Malley, pushed to legalize gay marriage in their states.

Republicans’ dilemma

Gay rights typically have been the domain of Democrats, but Republicans are debating a course change amid a self-reckoning after their losses in November.

The party platform last year stated “marriage, the union of one man and one woman must be upheld as the national standard.” A Republican National Committee election postmortem released last week said: “Already, there is a generational difference within the conservative movement about issues involving the treatment and the rights of gays — and for many younger voters, these issues are a gateway into whether the Party is a place they want to be.”

Ohio Republican U.S. Sen. Rob Portman recently said he was newly in favor of gay marriage because his son is gay. U.S. Sen. Rand Paul, R-Ky., said the issue could be solved by the government getting out of marriage entirely and letting consenting adults define their relationships as they may.

Still, it’s hardly a GOP stampede. When the Washington news outlet Politico asked U.S. Sen. Saxby Chambliss, a Georgia Republican, about gay marriage he replied: “I’m not gay. So I’m not going to marry one.”

At this month’s Conservative Political Action Conference outside Washington, organizers excluded the pro-gay GOProud group as a sponsor, but a forum featuring the head of GOProud and others advocating for same-sex marriage from a conservative viewpoint was packed with hundreds of interested attendees, though most were on the younger side.

“Look around the room; you’re looking at the new conservative coalition,” GOProud’s Jimmy LaSalvia said. “When history is written, you can say you were there.”

Ralph Reed, the former head of the Christian Coalition and former chairman of the Georgia GOP, disagreed.

Reed runs the Duluth-based Faith & Freedom Coalition, a group that organizes social conservatives. He eagerly rebuts arguments from those who say Republicans need to ride the public opinion wave and change their stance.

He points out that in the states where it passed, gay marriage earned far fewer votes than Obama. He acknowledged a public opinion shift, but said polling on social issues ebbs and flows – pointing to abortion rights and gun control as two issues that used to be more popular in previous decades than they are now.

Reed said supporting gay marriage would discourage the GOP base of evangelical Christians — 83 percent of white evangelicals told Pew same-sex marriage conflicts with their religious beliefs — while not peeling away many voters from Democrats, who always will be more vocal about advancing gay rights.

“Mitt Romney actually got more evangelical votes than any Republican candidate for president in U.S. history,” Reed said. “That is success. And you don’t want to take that level of success and start tinkering with it and rolling a grenade into your own foxhole.

“There may be other things that need to be done to improve the Republican Party’s image, but throwing cold water on evangelicals is just plain stupid.”

Rosenwald said a better parallel than guns or abortion for public opinion on gay marriage would be interracial marriage, to which opposition has gradually evaporated over several decades. U.S. Rep. John Lewis, an Atlanta Democrat, agreed. Lewis was a major figure in the civil rights movement and has publicly backed same-sex marriage for years.

Lewis said when Martin Luther King Jr. was asked about interracial marriage, he would respond: “Races don’t fall in love and get married. Individuals fall in love and get married.” Lewis said he applies the same principle to gays.

“I think one day, and not in any too distant future, this will no longer be an argument and won’t be a great discussion,” Lewis said. “We’ve come so far as a society, and it’s just going to be the norm.”