Change has swept the country since then, a shift in public opinion so dramatic that advisers to President Barack Obama figure he took only a small political risk in announcing his Justice Department will no longer defend the 1996 law defining marriage as between a man and a woman.

Republicans are sizing up the development cautiously, some with a strong hunch that swing voters may recoil from Obama because of it — particularly Catholic voters in the industrial heartland and married suburban voters in border states.

In the middle of the Clinton era, the public’s view of gay marriage was clear. As he began his second term, same-sex marriage met with the approval of only 27 percent of the population. Today, that number stands at 42 percent.

“This is just not as much of a societal no-no as it was back in Clinton days,” said Andrew Kohut, president of the Pew Research Center in Washington. “Times have changed.”

Of greater political significance, however, is that nearly half of independents support gay marriage, a position that the Democratic president hasn’t even gone so far as to embrace. And it is independent voters who will decide the presidential election in 2012.

“It’s simply not an issue that has the same kind of resonance that it had in 2000 or 2004,” Kohut said.

The decision to stand down on the DOMA will certainly stir up Republican base voters, but it also has the potential to help Obama with a liberal base whose enthusiasm for him has been flagging.

While House Speaker John Boehner, R-Ohio, did not rush to the microphones to talk about it Wednesday, conservatives think the issue may help define their party at a critical moment. It will draw social conservatives to the polls in greater numbers, said Ralph Reed, chairman of the Faith and Freedom Coalition. It could also make moderates think twice about voting Democrat, he said.

“This could definitely turn off independent voters, especially if the ones who go to the polls tend to be conservative, as was the case in 2010,” said Reed, noting the power of swing Catholic voters. “They are not necessarily social issue voters, but they are turned off by what they perceive as radicalism or extra-judicial activism by a politician on these issues. It speaks to Obama’s core beliefs, and not in a way that enables swing voters to identify with him.”

Progressives, meanwhile, think Obama took little to no political risk by dropping the DOMA defense. Obama has said in recent months that his attitude about gay marriage is “evolving,” and his press secretary specifically said the president came to the decision that the law is unconstitutional independent of his personal views.

The president has friends and staffers who are gay, and Obama has suggested in interviews that his thinking is affected by how much marriage means to them.

Perhaps not coincidentally, the gay rights movement has spent the last year talking about the issue in just such terms. In past debates over gay marriage at the state level, gay activists have focused on the rights and benefits they and their partners are denied because they can’t marry.

About three years ago, researchers at one progressive think tank concluded that line of logic had won all the support it could from the moderate slice of the electorate.

“We asked people how they think about marriage, and we found that they don’t think about their own marriages in terms of rights,” said Lanae Erickson, deputy director at the Third Way think tank. “We asked, ‘Why do you want to get married?’ and they talked about loving each other, taking care of each other.”

When the researchers framed their questions in those terms, Erickson said, the moderates they were studying began to change their answers about gay marriage, often in the middle of an interview.

In the past year, gay marriage advocates have rolled out ads that emphasize love, partnership and care, which Third Way researchers partially credit for an uptick in support.

Ironically, how the issue plays in the next election may have very little to do with how and whether people get married. With the economy and jobs at the forefront of people’s minds, social issues are losing their power to move voters, said Mark McKinnon, a strategist who worked with both George W. Bush and John McCain.

As a result, gay marriage is not as effective as a wedge that splits the party’s base.

“The wedge has lost its edge,” he said.