"African-Americans are generally opposed to discrimination, but on marriage they need to sort out the distinctions between legal equality and religious belief," said Sharon Lettman, spokeswoman for People for the American Way Foundation. "Most people haven't had a chance to have that conversation. The workshops we did at the NAACP's California state convention last weekend make it clear that people are hungry for it," Lettman said.
In May, the state legalized gay marriage, drawing gay couples from around the world and buoying sales tax coffers and the tourist industry. Same-sex marriage is also legal in Connecticut and Massachusetts.
Arizona and Florida voters face similar legal bans on Election Day, but all eyes are on California. At least 64,000 people from the 50 states and more than 20 countries have given money to support or oppose Proposition 8.
Many like Tony Perkins, president of the Family Research Council, a conservative Christian lobby based in Washington, have flown to the state to pursue the fight. He says that the proposition is "more important than the presidential election."
"We've picked bad presidents before, and we've survived as a nation," he said. "But we will not survive if we lose the institution of marriage."
Just one week before the election, campaign finance records show contributions totaling more than $60 million, according to The Associated Press.
"It's a staggering amount," said Matt Coles, director of the LGBT Project at the American Civil Liberties Union, which opposes the ban. "California is a cultural trendsetter. If voters decide same-sex couples can marry, it has an enormous influence."
Polls released last week from the Public Policy Institute of California showed the fight to defeat Proposition 8 was ahead by eight percentage points, but insiders say it's a dead heat.
"This election is eminently winnable or losable," Coles told ABCNews.com.
"Proponents have 40 percent of the vote nailed down," he said. "We are convinced we have 40 percent of the voters nailed down. The remaining group of people is conflicted. They don't like gay marriage, but they don't like taking something away from other people."
Greg Herek, a University of California psychology professor who specializes in research on sexual orientation, said as a group, blacks, even those who support gay rights, tend to oppose same-sex marriage.
But "age may override race," said Herek, who opposes the ban. "It's true the African Americans may turn out to vote against Proposition 8, but the younger may be more supportive of gay marriage."
"I don't have a crystal ball and it's a bit of a cliffhanger, but the Obama and [John] McCain race will be over early in the evening," he said. "We'll be up late with Proposition 8."
Supporters of the effort have made "significant inroads" into the Chinese and Korean church communities, according to Karin Wang, who works with API Equality-LA, a group that represents Asian Pacific Islanders.
"Collectively, these ads are all continuing a pattern of misinformation," Wang told ABCNews.com, "namely, the use of arguments that in mainstream media would appear ridiculous and illogical, as well as outright homophobic."
Ads in the Chinese media warn of "evils," such as polygamy or incest, and laws that protect gay students as "opening the door to all sorts of chaos in the schools," she said.