In the space of about a decade, public opinion has flipped on gay marriage.
About 60 percent of Americans opposed legalizing same-sex marriages in 2004, while just 35 percent supported it. By September of 2014, a majority—52 percent—favored the legalization of gay marriage, according to a Pew Research poll.
During that time, support for gay marriage has increased amongst every demographic category that Pew polled; it's up amongst the young and the old, conservatives and moderates, men and women, Hispanics and blacks, the religious and the non-observant. It's one of the most dramatic public opinion shifts in recent memory.
However, as Greg Sargent notes over at The Washington Post, the shift hasn't been equally dramatic in every category. Republicans, he notes "are all alone in opposing legal gay marriage, by 54-40." And white evangelical Protestants, a large and influential GOP voting block, make up the core of the nation's continued resistance.
With a major Supreme Court decision that could legalize gay marriage in every state due later this year, the issue is likely to come up in the GOP primary race. As Sargent writes:
The GOP hopefuls are already engaged in a delicate dance on marriage equality, as they seek to position themselves in advance to navigate the fallout from a potential Supreme Court decision this spring that could declare a Constitutionally protected right to gay marriage across the county.
CNN has a good overview of the jockeying underway among the GOP candidates in advance of this decision. Marco Rubio, Mitt Romney, and Jeb Bush are calling for respect for the courts' decisions on this matter and/or respect and understanding for people on both sides of the issue.
But Ted Cruz and Bobby Jindal are suggesting continued resistance; both have talked about a Constitutional marriage amendment. Mike Huckabee has said states should not be bound by such a decision, and on Meet the Press yesterday, he seemed to stick by that position.
I suspect Sargent is right that the issue will find its way into the primary race. Huckabee is virtually certain to talk about it, even if he doesn't run, and he's influential enough with evangelical voters that other candidates will need to respond. The issue will divide largely along the lines that Sargent lays out, with a moderate block that takes a relatively non-confrontational (although probably not enthusiastic) approach, and a more outspoken faction that prioritizes continued opposition.
Depending on who wins the Republican primary, that debate will probably bleed into the general election campaign to some degree, although I wouldn't expect it to be a major issue, unless the GOP candidate really fumbles the response or decides to make it a major issue—which, given the way the polls are running, is probably not a great idea.
After that, however, I suspect that it will be over. Not over in the sense that no one in America ever speaks a word in opposition to gay marriage again, but over in the sense of it being a meaningful political issue. As Ross Douthat has suggested (and as Sargent notes), evangelicals may simply view the fight as lost and decide to let the issue rest.
But more than that, Republican candidates are likely to have a harder time generating support by opposing gay marriage, because there are likely to be fewer and fewer Republican voters who oppose it.
Yes, the evangelical base of the GOP remains the most opposed to gay marriage of any cohort in the country, but the trend is still toward increased support. Since 2001, Republican support for gay marriage has risen by 9 points, according to Pew, and by 11 points amongst those who identify as conservative. White evangelical Protestants have been the slowest to show more support, but even there, support has risen by 8 points since 2001.
The trend is likely to continue. Younger evangelicals, in particular, are much more likely than their older counterparts to support gay marriage: One 2010 survey found that 44 percent of evangelicals under 35 oppose gay marriage, compared to 63 percent of evangelicals older than 35. As today's young evangelicals grow up, opposition to gay marriage will erode further still.
The alternative, of course, is that, for whatever reason, the trendlines stop or reverse, and public opinion shifts back against gay marriage just as it as has shifted in favor of it. Perhaps a dedicated core of opponents continue, and their continued activism makes it difficult for the GOP to completely leave the issue behind.
This is not impossible, but I don't think it's very likely. The most obvious inciting incident for such a reversal, this year's Supreme Court decision, isn't likely to spark significant pushback, because it's widely expected that the High Court will give its blessing to gay marriage everywhere, because the issue has already been extensively litigated in state courts, and because it would be following public opinion rather than leading it. For the last decade, the arguments on both sides have been aired over and over again, and, in the court of public, it seems pretty clear that opponents of gay marriage lost.
Most Republicans know this, even if they won't always acknowledge it. And that's why my guess is that 2016 will be the last hurrah for significant national political opposition to gay marriage—a final opportunity for some of the candidates to give voice to those who still reject it and still want their rejection to be part of the nation's political identity.
You can already see the ground being prepared for this shift. In the GOP's less socially conservative circles, it's already a non-issue. And even amongst the evangelicals, it's not the lightning rod it once was: At this year's Values Voter Summit, Michele Bachmann, who once implicitly compared gay marriage to incest and backed a state amendment prohibiting it, declared gay marriage "boring," saying that it's "not an issue."
The Supreme Court and lingering social conservative opposition are likely to ensure that it will be an issue in the next presidential campaign. But after that, no matter who takes the White House in 2016, I suspect it won't be. Most of the public has already shifted, and it won't be long before the GOP follows.