By CHARLES BABINGTON
WASHINGTON (AP) — Public opinion about same-sex marriage has changed so rapidly that President Barack Obama's historic embrace of it may pose as many political risks to Republicans as to the president and his fellow Democrats.
The president's dramatic shift on the issue — a watershed moment in U.S. politics, even if many people felt it was inevitable — is the latest sign that Democratic hopes increasingly rest on younger, college-educated and largely urban voters, whose lifestyles are shaped by social mobility more than religious and community traditions. Many young adults find the notion of discriminating against gays and lesbians as incomprehensible as their parents' and grandparents' accounts of living through racial segregation.
Yet same-sex marriage remains provocative in some places, including once-reliably Republican states such as North Carolina, where Obama won a narrow but stunning victory in 2008. Only hours before his Wednesday announcement on ABC News, North Carolina voters turned out in huge numbers to approve a constitutional ban on same-sex marriage.
The immediate reactions to Obama's statement on gay marriage weighed the political tradeoffs between embracing a social trend that's important to Democrats' liberal base, and risking potentially intense opposition from social conservatives in battleground states.
Mainstream Republicans, for the most part, moved warily. They focused their comment on the political calculations involved, not on the actual substance of letting same-sex couples marry.
Democrats, meanwhile, said Obama at last had found a cause that could begin to recapture some of the excitement of his barrier-breaking 2008 "hope and change" campaign.
"This gives the Democrats a fresh chance to mobilize young people and other base voters they need to turn out in November," said Democratic strategist Doug Hattaway, who worked for Hillary Rodham Clinton in the 2008 presidential primaries. "Many of them turned out to make history in 2008, and they will find this leadership from the president inspiring."
Hattaway noted that polls show substantial public support for same-sex marriage. "Mainstream Republicans aren't likely to make too much hay out of this," he said. "The smart ones realize that the GOP's gay-baiting threatens to alienate a whole generation of voters."
Initial reaction to Obama's announcement on ABC News suggests Hattaway is right.
"The president's position on gay marriage has been one of cold political calculation," said Terry Holt, one of several Republican consultants who steered clear of the issue's moral and religious implications. He said Obama seeks to "win over a group of voters that he absolutely has to have to get re-elected."
House Speaker John Boehner, arguably the nation's highest-ranking Republican, told Fox Business Network: "I have always believed that marriage was between a man and a woman. But Republicans here on Capitol Hill are focused in on the economy."
Mitt Romney, the party's presumptive nominee for president, on Wednesday restated his opposition to same-sex marriage, which he called "a very tender and sensitive topic."
That's not to say Obama's move is risk-free. It could energize social conservatives in North Carolina, Virginia, Florida and other states that Obama carried four years ago.
It's hard to say how the dynamic might play out. A minority of Americans care intensely about gun ownership rights, but the highly organized National Rifle Association has played a disproportionately powerful role in that area for years — so much so that Democrats including Obama rarely talk about gun control any more.
For now, few veteran Republican operatives seem to see a similar dynamic for gay marriage. Brian Nick, a North Carolina-based GOP consultant who closely followed the state's referendum banning same-sex marriage, played down the notion that Obama's move could cost him a chance to win the state again.
"I think the economy is going to be the issue that's voted on" in November, Nick said. "President Obama is clearly a liberal's liberal, and this is just another example."
But the embrace of same-sex marriage is likely to inspire the Democratic base as much as it might turn off persuadable centrists, Nick said. He called the issue "sort of a net wash" in North Carolina.
Some gay-rights advocates said Obama's move wasn't particularly courageous or pioneering. Former Vice President Dick Cheney and former first lady Laura Bush are among prominent Republicans who have endorsed same-sex marriage.
A new AP-GfK poll of adult Americans showed Obama with a 21 percentage point lead over Romney on the question of who is most trusted to handle "social issues such as abortion and same-sex marriage."
Starting last year, small majorities of Americans told the Gallup poll that gay marriage should be legal.
Republican consultant Matt Mackowiak said Obama needs to fire up liberal potential donors and seems willing to worry about blue-collar workers in swing states later.
"Obama's decision will hurt him in Indiana, Virginia, North Carolina, rural Pennsylvania, northern Florida, rural Missouri, lots of places that he needs," Mackowiak said. "The map just improved for Mitt Romney."
Perhaps. But few Democrats expect Obama to try hard in Indiana and Missouri. And he can easily win re-election without North Carolina and Virginia, provided he carries Ohio or Florida and doesn't lose states such as Michigan, Wisconsin and Pennsylvania.
Jen Psaki, a former Obama aide, said Democrats might be able to turn the issue against Romney.
"In his pursuit of acceptance by conservatives," she said, "Mitt Romney's support for a federal marriage amendment would be the first time we amended the Constitution to deny Americans equal rights, which is alarming to most people."
It seems highly unlikely that the U.S. Constitution will be amended to ban or safeguard same-sex marriage. Obama's comments Wednesday were more symbolic than substantive. But symbols matter when they come from the White House.
Democrats believe the president has his finger on the pulse of a fast-changing society. From a presidential election standpoint, opposition to same-sex marriage will matter only in the handful of states truly up for grabs on Nov. 6. If that opposition is sufficiently intense and organized, it could deal a surprising blow to the president.
For now, Romney, Boehner and mainstream GOP strategists seem more willing to focus on the struggling economy.
Charles Babington covers national politics for The Associated Press.