"We thank Barack Obama, even though he's not supporting it, for helping us," says Sonja Eddings Brown, of an anti-gay-marriage group called Protect Marriage. "We think it's going to push us over the top."
Obama is expected to bring African-American voters out in record numbers, and those voters are seen as often being more conservative on issues involving homosexuality.
Pastor Edward Smith of Zoe Christian Fellowship has been urging members of his Los Angeles area church to vote for the gay marriage ban.
"Marriage has always been defined as a man and a woman," Smith says.
For Smith, it's the most significant item on the November ballot.
"This issue is more important than who becomes president of our states to me and to our Christian believers," he says.
But many African-American supporters of gay marriage see it as a civil rights issue, with gays fighting familiar battles, Blackstone reports.
"We were denied the right to marry a person of another race," says Alice A. Huffman, president of the California chapter of the National Association For the Advancement of Colored People. "Any time government intervenes and tells you what you can or can't do, it's a denial of your rights."
The California NAACP is trying to mobilize voters against the gay marriage ban, but at a meeting this past week showed, it's not an easy sell.
"If you believe in God and the Bible, how do you reconcile same gender marriages with Genesis 1:27 and 28?" asked one Obama supporter who is still undecided on the gay marriage ban. The Bible verse referenced is a commandment that called on the first man and woman to "be fruitful" and multiply.
While Obama himself does not support gay marriage, he says California's law allowing it should be left as it is. That has left some of his supporters facing a dilemma on Election Day.
"I don't have a problem with civil unions, but when it comes to marriage, and the holy sanctity of marriage, that's where I'm conflicted," says Jacquelynn Hawthorne, an Obama supporter.
That inner turmoil makes her an undecided voter on the gay marriage ban, Blackstone reports. And although the ban seems to be losing in the polls right now, those voters could make all the difference.