Support for Gay Marriage Outweighs Opposition in Polls

President Obama’s decision to endorse same-sex marriage undoubtedly entails some political risk, but recent polls suggest that public opinion is increasingly on his side.

According to surveys included in the PollingReport.com database, an average of 50 percent of American adults support same-sex marriage rights while 45 percent oppose it, based on an average of nine surveys conducted in the past year.

This is a reversal from earlier periods: support for same-sex marriage has been increasing, and opposition to it has been decreasing, at a relatively steady rate of perhaps two or three percentage points a year since 2004.

It should be remembered that support for same-sex marriage in polls has not necessarily translated into support at the ballot booth. On Tuesday, North Carolina became the latest state to adopt a Constitutional ban on same-sex marriage and did so by a margin of about 20 percentage points, somewhat larger than polls forecast. The North Carolina measure also banned domestic partnerships and other types of civil unions.

Still, even if polls have sometimes overstated support for same-sex marriage, and if some of the Americans who support same-sex marriage are less likely to turn out to vote than those who oppose it, the issue now seems to have a bit of wiggle room, with supporters slightly outnumbering opponents in recent national surveys. In addition, there is no longer evidence of an “enthusiasm gap” with respect to same-sex marriage: an NBC News/Wall Street Journal poll in March found that 32 percent of Americans said they strongly favored same-sex marriage, while 31 percent strongly opposed it.

Mr. Obama’s electoral calculation may hinge upon three questions related to the politics of the Democratic and Republican base. Social issues often do more to reinforce the loyalties of each party’s core voting groups than to sway the opinions of swing voters, especially in middling economic circumstances.

First, there is the question of how much emphasis Republicans will choose to place on gay marriage, which could motivate their base but increasingly divide Republican voters and independent ones. Next, how much might Mr. Obama’s stance be embraced or opposed by African-Americans, who have more conservative attitudes about same-sex marriage than other Democrats? Finally, could the issue motivate younger liberals and Democrats, who tend to support same-sex marriage, to turn out for Mr. Obama when they might not otherwise?

Nevertheless, with the broader shift in public opinion, Mr. Obama is not accepting the same risks by endorsing same-sex marriage that he would have even a year or two ago.

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