Obama Says Same-Sex Marriage Should Be Legal

“At a certain point, I’ve just concluded that for me personally it is important for me to go ahead and affirm that I think same-sex couples should be able to get married,” Mr. Obama told ABC News in an interview that came after the president faced mounting pressure to clarify his position.

In an election that is all but certain to turn on the slowly recovering economy and its persistently high jobless rate, Mr. Obama’s stand nonetheless injects a volatile social issue into the campaign debate and puts him at even sharper odds with his presumptive Republican rival, Mitt Romney, who opposes same-sex marriage and favors an amendment to the United States Constitution to forbid it.

Hours before the president’s announcement, Mr. Romney, the former governor of Massachusetts, restated his opposition to same-sex marriage in an interview with KDVR-TV, a Fox News affiliate in Colorado.

“When these issues were raised in my state of Massachusetts, I indicated my view, which is I do not favor marriage between people of the same gender, and I do not favor civil unions if they are identical to marriage other than by name,” Mr. Romney said. “My view is the domestic partnership benefits, hospital visitation rights and the like are appropriate, but that the others are not.”

Public support for same-sex marriage is growing at a pace that surprises even professional pollsters as older generations of voters who tend to be strongly opposed are supplanted by younger ones who are just as strongly in favor. Same-sex couples are featured in some of the most popular shows on television, without controversy.

Yet time after time, when the issue is put to voters in states, they have chosen to ban unions between people of the same gender or to defeat measures that would legalize same-sex unions. Just Tuesday, North Carolinians voted overwhelmingly to add a ban to their state constitution, and Republican leaders in the Colorado House blocked a vote on legislation to allow civil unions; North Carolina and Colorado are considered swing states in presidential politics.

Nationwide, according to the pollster Andrew Kohut of the nonpartisan Pew Research Center, a plurality of swing voters favors same-sex marriage, 47 percent to 39 percent, and outside the South the margin widens to a majority of 53 percent in favor and 35 percent opposed; in the South, a plurality of 48 percent opposes same-sex marriage. Swing voters generally do not have strong opinions on the subject, Mr. Kohut said, though in the South 30 percent of swing voters say they are strongly opposed.

Supporters of same-sex marriage were quick to praise the president’s decision to speak out.

“President Obama’s words today will be celebrated by generations to come,” said Chad Griffin, the incoming president of the Human Rights Campaign, a gay advocacy group. “For the millions of young gay and lesbian Americans across this nation, President Obama’s words provide genuine hope that they will be the first generation to grow up with the freedom to fully pursue the American dream. Marriage — the promise of love, companionship, and family — is basic to the pursuit of that dream.”

Senator Kirsten E. Gillibrand, Democrat of New York, called the president’s statement “a watershed moment in American history” that would aid efforts to overturn the Defense of Marriage Act barring federal recognition of same-sex marriage.

Mayor Michael R. Bloomberg of New York said, “No American president has ever supported a major expansion of civil rights that has not ultimately been adopted by the American people, and I have no doubt that this will be no exception.”

Some supporters saw the president’s announcement in more political terms.