LOS ANGELES — California's fiercely contested gay marriage ban took the lead in early returns Tuesday, after one of the most expensive and closely watched campaigns in the nation divided voters across religious and political lines.

Pitched as a critical moral question of our time by supporters, and an issue of equality and justice by opponents, Proposition 8 aroused the most passion of any state ballot measure this year.

"We are very, very positive," said Sonja Eddings Brown, deputy communications director for the Protect Marriage coalition. "It's been a tough fight. We just feel that we're glad to be in a state where ... marriages should be defined between a man and a woman."

Lorri L. Jean, chief executive officer of the Los Angeles Gay and Lesbian Center, said the No on 8 campaign was still holding out hope. The fate of the proposition was still undecided as of press time.

"(If we lose) it will be a devastating blow, but it won't be the end of the story," Jean said. "We will be sad, we will be angry, but we will have to pick up ourselves up and carry on."

The measure had drawn huge national attention as volunteers and millions of dollars in donations poured in from other states to support or defeat the measure.

From Catholics and celebrities to Democrats and Republicans, the initiative divided some groups and united others in a pitched, sometimes ugly political fight. Both sides have spent a combined $70 million to reach undecided voters through rallies, television ads, the Internet and marathon-paced phone banks.

Proponents of the ban say it restores traditional values and acts as a moral compass to steer California's society in the right direction. Opponents say it discriminates against a section of the population, denying them the same right as opposite-sex couples to economic, social and other benefits of marriage.

Locally, No on Proposition 8 supporters ratcheted up their efforts throughout Election Day and into the night to reach voters at the polls. Meanwhile, the Yes campaign fought hard to draw out the vote, relying heavily on ads that said children would be forced to learn about gay marriage in public schools.

"If Proposition 8 passes, there will be sadness, disappointment and tears," said Sky Johnson, deputy campaign manager for the No on Proposition 8 campaign.

The Yes on 8 campaign reached out to religious groups and others in and outside California to support the ban.

"Since the California Supreme Court legalized gay marriage, we have discovered gay advocates ... (teaching) gay marriage and sexuality in our public schools," said Sonja Eddings Brown, deputy communications director for the Protect Marriage coalition.