Nate Cohn at TNR argues 2012 is the flip side of 2004:
What's changed over the past eight years that's allowed the culture war to be turned on its head? On an issue like gay marriage, changing public views is part of the issue. But more broadly, Democrats are benefiting in the cultural war from Obama’s ability to ensure the allegiance of socially conservative non-white voters, and they’re taking advantage by going on the offensive.
...As a result, the old culture war calculus has flipped from favoring Republicans to Democrats. If Obama can hold conservative minority voters, then Obama could win the election by simply by doing as well as Kerry did among white voters in 2004. One way to do that? Re-run the debates that dominated the 2004 campaign, like gay marriage and tax cuts for the wealthy. And that appears to be the Obama campaign’s choice, even while adding new issues like contraception, where Democrats are on even safer ground than they are on gay marriage. Here’s a different way to frame the issue: gay marriage is more popular among white voters than Obama, so he stands to make gains among those voters. Now, it’s not exactly this simple. Obama has suffered losses among white voters without a college degree and many of them supported Kerry in 2004. But Obama is doing better among college-educated voters than Kerry did, and that makes it even easier for Obama to pursue progressive social positions. Now supporting gay marriage reinforces a larger number of college educated white Obama supporters, and alienates fewer white working class Obama supporters.
The Romney campaign appears to have made a similar calculation: at the moment, there aren’t advertisements about gay marriage, even in North Carolina, where gay marriage was soundly defeated just a few months ago. Why? The Obama voters opposed to gay marriage are generally, although hardly exclusively, African American. The Romney campaign probably shouldn’t waste it’s time appealing to that particular voting bloc, especially since there are plenty of moderate Republicans who support gay marriage in North Carolina’s better educated metropolitan areas. If the Romney campaign gets desperate, they might try and use gay marriage to rebuild their support among socially conservative working class voters skeptical of outsourcing, Bain, and Romney’s tax returns. But gay marriage probably doesn’t have a role to play in a close election—no side clearly benefits.
With Obama all but assured an overwhelming share of the non-white vote, Democrats have free-reign to pursue more liberal stances on social issues. While in the past, such a stance would risk alienating socially conservative minorities and white working class voters, Obama’s identity and immigration policy all but ensures elevated levels of support among African Americans and Latinos, while Obama’s lesser burden among white working class voters paradoxically allows Obama to pursue policies opposed by a majority of white working class voters.