The Golden State went a deep shade of blue yesterday, but Barack Obama’s popularity might have had unintended consequences down the ticket.

The uneasy spread of gay marriage across the United States lost its biggest test in the form of Proposition 8, a response to the California Supreme Court’s decision earlier this year that “limiting the designation of marriage to a union ‘between a man and a woman’ is unconstitutional”.

The Proposition sought to amend the state’s Constitution to “Eliminate the right of same-sex couples to marry in California” – a recipe for chaos, given that low-information voters prefer to maintain the status quo by rejecting most Propositions; in this case, a ‘no’ vote would have entrenched gay marriage.

It appears that it will pass with 52 percent of the vote, with 95 percent of precincts reporting, throwing the approximately 18,000 gay marriages that have taken place since the May 15 decision into legal limbo. Legal experts are divided on the status of these unions; Attorney-General Jerry Brown suggests that any challenge to existing marriages will be ultimately decided by the California Supreme Court or a higher authority. The Yes On 8 campaign is refusing to say whether it will lead these challenges.

California’s ‘San Francisco values’ get a lot of exposure in Republican stump speeches, but the state’s assent to same-sex nuptials was always far from guaranteed. In 2000, gay marriage was rejected by 61 percent of voters. Though polls throughout the campaign season were generally positive, the result remained uncertain.

One reason may have been Barack Obama: his candidacy was expected to bring record numbers of African-Americans to the polls. The problem is that the black community, for whatever reason, is the least receptive to the idea of gay marriage, approving of the Proposition by an astonishing 20 points according to SurveyUSA. The hispanic community is not far behind. The concern for activists was that Obama’s unique drawing power and unprecedented get-out-the-vote organisation might see the progressive cause undermined by these socially conservative mega-minorities.

The results suggest their fears were well founded: 70 percent of blacks supported the Proposition, according to a CNN exit poll, along with 53 percent of Latinos.

Obama opposed Proposition 8, but the mental gymnastics of his opposition were far from convincing:

I’ve stated my opposition to this. I think it’s unnecessary,’ he told MTV, ‘I believe marriage is between a man and a woman. I am not in favor of gay marriage. But when you start playing around with constitutions just to prohibit somebody who cares about another person, it just seems to me that’s not what America’s about.

The result brings to a close the latest battle in this long-running war, and an especially divisive one at that.

Supporters of the Proposition avoided the explicitly Biblical arguments, instead basing their opposition on a desire to protect tradition marriage and religious freedom. Though they tried to avoid the impression, it’s hard to deny that Big Religion had a stake. Mormon money financed up to 40 percent of the campaign, according to the Wall Street Journal. Last weekend San Diego hosted a rally of evangelicals led by the influential and well-connected James Dobson, promoted as ‘battle between light and darkness’, where the faithful were asked to ‘cry out to God for the deliverance of homosexuals’.

Though these rallies seemed like outdated remnants of the 2004 campaign, they were been backed up by widespread and well-targeted advertisements. One showed San Francisco’s controversial mayor Gavin Newson, who tried to legalise gay marriage at the city level in 2004, declaring “this door is wide open now, it (gay marriage) is going to happen, whether you like it or not.”

Another warned that California’s public schools will be forced to teach about gay marriage (“Mom, guess what I learned in school today? I learned that a prince could marry a prince!”) against the objections of parents. The latter advert was credited with reigning in the 17-point lead held by opponents of the Proposition during the summer. It also reframed the debate – voters ready to believe that gay marriage would have no effect on their lives came to see it as a threat to education, children and their traditional values.

In response, the No On 8 campaign rolled out its own big guns: Bill Clinton opposing the bill in a series of robocalls, telling voters that:

Proposition 8 would use state law to single out one group of Californians to be treated differently – discriminating against members of our family, our friends and our co-workers. If I know one thing about California, I know that is not what you’re about.

Samuel L. Jackson narrated the last round of ads, telling Californians that the Proposition ‘is unfair, and it’s wrong.’ Arnold Schwarzenegger, Apple, Google, Yahoo and California’s Senators all declared their opposition.

Edward Muna, an activist on the local No On 4, No On 8 campaign, said the campaign couched its arguments in civil rights, trying to convince Californians that “this isn’t about what you think about marriage, what I think about marriage, or what religion thinks about marriage. It’s about being able to declare love in equal status to heterosexual couples.” Both sides fought the battle at the grassroots level, around dinner tables, on front lawns and in churches and synagogues. “It’s an old style political campaign,” Muna said, “if it doesn’t affect them, it affects a friend…we’re encouraging supporters to actually talk with their friends and family.”

But ultimately, the progressive winds that swept the nation yesterday were clear in their endorsement of Obama, and clear in their rejection of gay marriage. Similar Propositions were passed in Arizona, Arkansas and Florida, bringing to thirty the number of states that have banned the institution, and perhaps revealing the first subtle cracks in the coming Democratic majority, and the limits of the nation’s liberal turn.

The morning after, gay activists recognise that this is a serious blow. They have not conceded yet, and there is talk of challenging the constitutional validity of the Proposition, but if they can’t convince Californians to accept gay marriage as legitimate, what hope the rest of the nation?

The campaign’s local headquarters, an organic food co-op, is scattered with the usual campaign debris — yard signs, t-shirts and pizza boxes — as well as c-ndoms plastered with slogans and encouragements to vote. The mood is somber, but according to Muna, they remain hopeful: “I’m expecting to start working harder. As long as they keep fighting, we will too.”