Opponents of Proposition 23, the ballot measure that would suspend California's landmark global warming legislation, have long argued that supporters of the measure were prepared to flood the state with money for the initiative.

But with little more than two weeks until the Nov. 2 election, that flood has yet to materialize. And the No on 23 campaign -- a coalition that includes environmentalists, venture capitalists, social justice groups and some of Silicon Valley's hottest cleantech companies -- is outpacing Yes on 23 in fundraising by more than a 2-1 ratio.

Donations of $1,000 or more must be filed with the California Secretary of State's Office within a 24-hour period, so fundraising tallies fluctuate daily. As of 1 p.m. Thursday, Yes on 23 had raised $9.1 million, while the various committees working to defeat Prop. 23 had raised $19.6 million, according to MAPLight.org, a nonpartisan research organization that tracks the influence of money on politics.

If you subtract the $2 million that Yes on 23 had to spend to gather signatures to put the measure on the ballot, the disparity is closer to 3-to-1.

A Sept. 26 Field Poll showed most voter blocs lining up on the "No" side, with many voters undecided.

The fundraising disparity is all the more noteworthy because many Californians have begun to cast their ballots by mail, and the window of opportunity to influence public opinion is closing. And with California awash in television ads for the gubernatorial and Senate races, it's increasingly hard to buy airtime.

"Most of the available airtime for political ads is locked up," said Barbara O'Connor, emeritus director of the Institute for the Study of Politics and Media at Sacramento State.

"It's pretty late in the game for a surge, especially since votes are already being cast," added Jack Pitney, a political-science professor at Claremont McKenna College. "Yes on 23 may have underestimated how much it would cost, and how intense the opposition would be."

Anita Mangels, a spokeswoman for Yes on 23, declined to talk specifically about the campaign's fundraising strategy and sought to put the focus on the deep pockets behind No on 23, including Thomas Steyer, a hedge fund executive with Farallon Capital Management in San Francisco who has donated $5 million and is co-chair of the No on 23 campaign.

"It appears that the billionaire hedge fund manager and the venture capitalists -- some from California, some from other states -- who are bankrolling the No on 23 campaign have decided that defeating Proposition 23 is a good investment that will reap them huge returns," Mangels said.

Steve Maviglio, a spokesman for No on 23, stressed Thursday that large, multimillion-dollar donations from the petrochemical industry could come in at any time, and he cautioned that No on 23's current fundraising advantage, while welcome, should be viewed as tenuous.

"These companies can write a check whenever they want, and they have a history of coming in late and heavy," Maviglio said.

Supporters of No on 23 include some of the most prominent names in Silicon Valley. Vinod Khosla, one of the nation's top cleantech venture capitalists, donated $1,037,267 this week. Tesla Motors of Palo Alto donated $25,000 -- the company's first political contribution. Other fundraisers are planned: Alan Salzman of VantagePoint Venture Partners plans to host a No on 23 fundraiser featuring Elvis Costello at Salzman's Atherton home Oct. 22.

Prop. 23 seeks to suspend AB 32, a law that seeks to limit the state's production of the emissions that cause global warming. Proponents of Prop. 23 say that when AB 32 is implemented, energy prices will rise and businesses will be forced to lay off workers or leave the state. The largest contributor to Yes on 23 to date is Valero, a San Antonio company that operates two refineries in California.

"Valero is monitoring the situation closely, and we remain enthusiastic and proud supporters of Prop. 23," said Bill Day, a spokesman for Valero. "We're not pulling back in any way."

Contact Dana Hull at 408-920-2706.

Follow her at Twitter.com/danahull.

PROPOSITION 23's
Top Contributors
In support
  • Valero: $4.1 million
  • Tesoro: $1.5 million
  • Flint Hills Resources:
    $1 million
  • Marathon Petroleum: $500,000
  • Adam Smith Foundation: $498,000
    Against
  • Thomas Steyer: $5 million
  • John and Ann Doerr:
    $2 million
  • The League of Conservation Voters: $1.2 million
  • Vinod Khosla: $1 million
  • Robert Fisher: $1 million
    Source: California Secretary of State's Office, MAPLight.org

    Top contributors AGAINST Prop. 23
    Thomas Steyer -- $5,000,000
    John and Ann Doerr -- $2,000,000
    The League of Conservation Voters -- $1,200,000
    Vinod Khosla -- $1,037,267
    Robert Fisher -- $1,000,000
    Source: California Secretary of State's Office, MAPLight.org