Four years ago, bipartisan majorities in the California Legislature approved a landmark clean energy bill that many hoped would serve as a template for a national effort to reduce dependence on foreign oil and mitigate the threat of climate change.

Now a well-financed coalition of right-wing ideologues, out-of-state oil and gas companies and climate-change skeptics is seeking to effectively kill that law with an initiative on the November state ballot. The money men include Charles and David Koch, the Kansas oil and gas billionaires who have played a prominent role in financing the Tea Party movement.

The 2006 law, known as AB 32, is aimed at reducing California’s emissions of carbon dioxide and other greenhouse gases to 1990 levels by 2020 and by 80 percent at midcentury. To reach these targets, state agencies are drawing up regulations that would affect businesses and consumers across the board  requiring even cleaner cars, more energy-efficient buildings and appliances, and power plants that use alternative energy sources like wind instead of older fossil fuels.

The prospect that these rules could reduce gasoline consumption strikes terror into some energy companies. A large chunk of the $8.2 million raised in support of the ballot proposition has come from just two Texas-based oil and gas companies, Valero and Tesoro, which have extensive operations in California. The Koch brothers have contributed about $1 million, partly because they worry about damage to the bottom line at Koch Industries, and also because they believe that climate change is a left-wing hoax.