(RELATED: Demographics of Gay Marriage)
Yet even while resisting gay marriage, shelving immigration reform, and abandoning gun control, Democrats have hemorrhaged support among those socially-conservative white voters in recent years. In 2008, John McCain won nearly three-fifths of both non-college whites and white seniors. In 2010, the Republican House candidates won over three-fifths of the vote from both groups-and routed "blue dog" Democrats in rural and blue-collar House districts. Most 2012 polls show Obama struggling with both groups and in particular facing an uphill climb to match the mere 40 percent of the vote he captured among non-college whites last time.
Nothing about the gay marriage announcement will make it easier for Obama to recapture those voters. "I don't know that it makes it worse, but it confirms or is part of a narrative about white conservative voters not supporting him," says Democratic pollster Anna Greenberg. "These groups have basically decided they are not for him, and some of them decided before November 2008 and some decided during health care." Obama's willingness to publicly reverse his gay marriage stand may represent a tacit admission that he has to win without many of those older and blue-collar whites-and he needs to excite the constituencies more likely to actually support him in 2012.
The modern Democratic coalition has three principal pillars: young people, college-educated whites (especially women), and minorities. And with those groups, gay marriage is generally a much more popular position. In the Pew survey, half of college-educated white men, a resounding 65 percent of college-educated white women and 68 percent of whites under 30 backed the idea. (In 2001, just 52 percent of younger whites backed gay marriage.) African-Americans, Hispanics and other minorities are much more closely divided on gay marriage, with the Pew survey finding just 40 percent of non-white men backing the idea. But it attracts support from 54 percent of minority women and retains plurality support among minorities overall.(That itself represents a major increase from as recently as 2007 when only about one-third of minorities backed gay marriage in Pew polling.)
In an interview after the 2010 election, David Axelrod, Obama's senior campaign strategist, cited as a model for the president's 2012 coalition, the electoral alignment that narrowly reelected Democratic Sen. Michael Bennet in Colorado during the GOP mid-term sweep. Bennet won despite a stampede toward the GOP among blue-collar and rural whites by mobilizing young people, minorities and socially liberal upscale whites, especially suburban women (he carried 60 percent of college-educated women according to exit polls).
Economic issues will unquestionably matter most in November. But Obama's embrace of gay marriage, like his more enthusiastic recent endorsement of comprehensive reform that provides a pathway to citizenship for illegal immigrants, may make it harder for him to hold states like North Carolina, Ohio and even Wisconsin, where the most socially conservative elements of the white electorate are heavily represented. (North Carolina with the big evangelical Christian population that powered approval of Tuesday's state referendum to ban gay marriage appears to be an especially big concern for Obama's team.) Yet these positions could also improve Obama's prospects of assembling a Bennet-like coalition in states defined by high education levels and diversity like Colorado, Virginia and even Pennsylvania, which Mitt Romney is targeting.