Shareholders have filed resolutions with three oil companies asking for their respective boards of directors to review political spending and policies in light of their support for overturning California's climate change law.

Occidental Petroleum, Valero Energy Corp. and Tesoro Corp. have collectively poured millions of dollars into the campaign for Proposition 23, which would suspend the Global Warming and Solutions Act of 2006, also known as AB 32, until the unemployment rate dropped to 5.5 percent for lower for one year. Unemployment in the nation's most populous state now stands at above 12 percent.

The Unitarian Universalist Association filed the resolution with Valero, while the Nathan Cummings Foundation was the primary filer in the Tesoro resolution. Green Century Capital Management filed the resolution with Occidental.

"That Valero and the other companies are using company money for such overt political purposes is both inappropriate and reflects poor governance. Beyond stifling California's fast-growing clean tech economy, rolling back this law will delay the nation's much needed transition to a clean energy economy and greater energy independence," Mindy Lubber, president of the nonprofit Ceres, and director of the Investor Network on Climate Risk, said in a statement Wednesday.

However, the groups filing the resolutions are relatively small shareholders of stock for the three companies, and the moves would probably not have an immediate impact on whether the oil companies will spend more money on the effort, the Los Angeles Times reported. For example, the Valero resolution wouldn't receive a vote until April, months after voters head to the polls in November to decide the fate of AB 32.

AB 32 is scheduled to go into effect in 2012 and seeks to reduce greenhouse gas emissions in the state to 1990 levels by 2020. A third of California's electricity would come from renewable sources by 2020 under the law.

A raft of cleantech companies, entrepreneurs and environmentalists on the other side of the debate over Prop 23 have raised more than $16 million to defeat the effort. As of Monday, Prop 23 backers had raised nearly $9 million.

A Reuters/Ipsos poll released last week found 49 percent of residents opposed Prop 23, with 37 percent voicing support, and 14 percent undecided.

Image CC licensed by Flickr user Omar Omar.