While the battle over same-sex marriage has been all but invisible in the presidential race this year, it is raging like a wind-whipped wildfire in California.

Conservative religious leaders from across the country are pouring time, talent and millions of dollars into the state in support of Proposition 8, which would ban same-sex marriage. They are hoping to reverse a California Supreme Court ruling in May that gave same-sex couples permission to marry, resulting in thousands of exultant same-sex weddings.

Similar marriage amendments are on the ballot next month in Arizona and Florida. But religious conservatives have cast the campaign in California as the decisive last stand, warning in stunningly apocalyptic terms of dire consequences to the entire nation if Proposition 8 does not pass.

California, they say, sets cultural trends for the rest of the country and even the world. If same-sex marriage is allowed to become entrenched there, they warn, there will be no going back.