The campaign against Proposition 23, the California ballot initiative that would suspend the state’s global warming law, took in more than a half million dollars in contributions this week. Meanwhile, fundraising by the oil companies backing the measure was so lackluster it prompted a plea for help from the petrochemical industry.

“A defeat for Proposition 23 in California could energize environmental fanatics around the country and in Washington to match California’s destructive policies with their own versions of AB32,” wrote Charles T. Drevna, president of the National Petrochemical & Refiners Association, in an email first reported by The New York Times. “We’ve raised about $6 million so far, but unfortunately in California’s expensive media market this is not enough to win the fight against environmental zealots led by Gov. Arnold Schwarzenegger, who seems hell-bent on becoming the real-life Terminator of our industry.”

“I am pleading with each of you,” Drevna continued, “for our nation’s best interest and for your company’s own self-interest, please contact me and tell me how much you can contribute to this critical effort as soon as possible. Nov. 2 is drawing near.”

The Texas oil companies backing the initiative made news recently when they secured a $1 million donation from the billionaire Koch brothers, who bankroll various right-wing causes. But the only sizeable donation to the Yes on 23 campaign this week came from Tower Energy Group, a Southern California-based petroleum wholesaler, which contributed $100,000 on Monday. Meanwhile, according to campaign finance records, the anti-Prop 23 forces have been having a pretty good few weeks.

On Monday, Susan Packard Orr, yet another daughter of David Packard, the late co-founder of Hewlett-Packard, contributed $250,000 to the No campaign. She joins her two sisters who have given a total of $201,895 to the effort to defeat Prop 23.

On Wednesday, William Patterson of SPO Partners, a Marin County, Calif., private investment firm, also gave $250,000. The California chapter of the Audubon Society stepped up with a $100,000 donation last week. Earlier in the month, Environment California, a non-profit, made a $100,000 contribution.

Another non-profit, the San Francisco-based Tides Foundation, put in $40,000 while a high-profile San Francisco real estate magnate, Douglas Shorenstein, contributed $25,000.

The big Silicon Valley venture capitalists, who vociferously oppose a ballot initiative that could derail the billions of dollars they’ve invested in green technology startups, have largely remained no-shows on the No on 23 donor roll. Though Tom Baruch, founder of CMEA Capital, did give $25,000 on Wednesday, and John Doerr, a leading green tech investor with Kleiner Perkins Caufield & Byers, is a notable exception with his $500,000 investment to defeat Prop 23.

If Silicon Valley’s venture capitalists decide to open their checkbooks, game on.