Supporters and opponents of a statewide measure expected to appear on November’s ballot aimed at defining marriage as between a man and woman are gearing up for a heated, expensive fight, both sides have told PolitickerCA.com.

“It’s really going to be the fight of our lives,” said Alice Keffler, a representative for Equality California, a gay rights organization that is leading the charge against the measure.

Keffler said she expected opponents of the measure to raise between $16-$20 million for the fight, while Andrew Pugno, an attorney who is helping to head up the effort to pass the measure, said he believed his side would need to spend between $10-$15 million. “It will be difficult, but it will be necessary,” said Pugno.

The Marriage Protection Act, which proposes changes to the state constitution, has not yet qualified for November ballot, but from all indications it will. Sponsors of the measure have submitted 1.1 million signatures to the Secretary of State’s office, more than the 763,790 needed. Supporters of the measure said they expected to know for certain in mid-June if the measure will qualify for the ballot.

Early polling suggests that voters in the state are evenly split over the issue of gay marriage. A poll conducted by Survey USA in the hours after the state Supreme Court issued its ruling last week that gay marriage is constitutionally protected showed 46 percent saying they agreed with the decision and another 46 percent saying they disagreed.

“I expect it to be a very vigorous campaign,” said Allan Hoffenblum, editor of the California Target Book.

Both sides raced to claim an edge in the upcoming fight. Pugno, pointing to the overwhelming 61 percent – 39 percent victory of Proposition 22, said that voters were unlikely to have changed their minds on the issue. “It’s a core, fundamental issue. It’s not something vulnerable to people changing their minds,” he said.

“I think a lot has changed,” Keffler countered, arguing that opponents would have more support this time around from the public in general and some Republicans.

One potential challenge for those who are fighting against the constitutional change is that early polling shows the measure attracting support from groups that typically align themselves with the Democratic Party, especially African Americans, Latinos, and Asians.

“This is a ballot measure that is going to split the traditional Democratic coalition,” said Hoffenblum.

What could help opponents of the measure expand their base of support is the support of Republican Governor Arnold Schwarzenegger, who provides an opportunity to expand their base of support.

Both sides are preparing messages for the campaign. Supporters, pointing March 2000 passage of Proposition 22 which defined marriage as between a man and a woman, say that the court’s decision provides them with an opening. “This court decision that declares war on the voters frames the issue. That is, the will of the voters versus judicial activism,” said Pugno.

“I think the Supreme Court’s decision will really focus the people’s attention on the courts,” said Mike Spence, the chair of the California Republican Assembly, who also helping to lead the fight to pass the measure.

Keffler said opponents of the measure have a straightforward counterargument. “Our message is a simple one: the Court’s role is to uphold the constitution, and that’s exactly what it did.”