BOB GARFIELD: In the last two weeks, two states have legalized same-sex marriage. First, the Iowa Supreme Court ruled that a law banning same-sex marriage was unconstitutional. Then Vermont became the first state to legalize same-sex marriage through its legislature. When it comes to public opinion, supporters of gay marriage are still a minority, but they're a growing minority. A recent CBS poll showed that 33 percent of Americans support same-sex marriage today, up from 22 percent in 2004. Scott Barclay, a political scientist at New York’s University at Albany, along with his colleagues, has been tracking that gradual shift in public opinion, going back to 1990, and found a major contributing factor for the growing public acceptance is newspapers. The research found that public opinion on gay marriage followed the opinion of newspapers and not the other way around. And when they controlled for variables, Barclay says they found newspapers’ influence was more significant than any other factor, more influential than everything from religious groups to Will and Grace.

SCOTT BARCLAY: In the vast majority of the states we looked at, papers had a cumulative effect. They gently pushed readers, over an extended period of time, towards same-sex marriage.

BOB GARFIELD: So in some places, newspapers that editorialized on this issue were, you know, roughly within the jaws of consensus. Other times they were going utterly against the tide of public opinion. Tell me about The Denver Post.

SCOTT BARCLAY: The Denver Post took an early position in support of civil unions, and they were unchanging in this position, despite the fact that there are clear indicators that the local audience for The Denver Post were hostile to same-sex marriage and civil unions for much of this period. The Denver Post, actually, in an editorial, mocked their audience by saying, we've been here all along, you were sort of wrong in the past.

BOB GARFIELD: Now, we've had people on this program look at data and tell us that editorial endorsements, for instance, have very little effect on the outcome of elections. And then there’s the question of gun control, which has been front and center on the editorial pages for decades, with very little apparent effect. People still claim Second Amendment rights that the newspapers say do not exist. How do you know that the correlation between a shift in public opinion has anything whatsoever to do with the editorials of the community papers?

SCOTT BARCLAY: I think there was greater unity among many of the newspapers we saw, so they had a more unified position than they do on, say, gun control or on other issues, or even on candidates. And I also think this was an issue that the newspapers thought of as something that they could have an impact [on], that they thought of themselves as being important players in this area, much more than some of the other issues that were occurring.

BOB GARFIELD: Along about the end of President George W. Bush’s first term, Karl Rove latched onto this wedge issue of gay marriage as evidence that the liberal elites were pushing America in a direction that America was loath to go. You know, looking at your research, it’s hard not to conclude that he was right. Was he right?

SCOTT BARCLAY: I would say no. What our research indicates to us is that a large amount of Americans actually had either no really fixed opinion or had a very easily changed position. One of the things that’s interesting for us is that even when states restrict same-sex marriage or there are constitutional amendments in a state, the more it was discussed, the more people had to think about it, the more they came to endorse this issue, slowly over time, but still they sort of moved on this issue.

BOB GARFIELD: Now yes, 22 percent to 33 percent, according to the CBS poll, documents quite a shift in public opinion, but 33 percent is still only a third of the electorate. Two to one against is a pretty dramatic ratio. Looking at these data, what would Sean Hannity say?

SCOTT BARCLAY: We think [LAUGHS] in 10 to 15 years, if the media activity continues, Sean Hannity will say what many other conservatives say about same-sex marriage, which is he would endorse it. And we think the reason we can take that position is ‘cause if we look back at interracial marriage, it was initially only at a 19 percent support level in 1968, one year after the Supreme Court, the U.S. Supreme Court, had acted in this issue. When we combine support for civil unions and support for same-sex marriage, then in many parts of the country we're approaching 60 percent of that region is actually in support of it. And so, on a lot of these issues, it’s not quite clear that 50 percent public opinion or above 50 percent public opinion is the key characteristic.

BOB GARFIELD: Scott, thank you very much for joining us.

SCOTT BARCLAY: Thank you.

BOB GARFIELD: Scott Barclay is professor of political science at the Rockefeller College of Public Affairs and Policy at the University at Albany.