Elon Musk. (David Paul Morris/Bloomberg)

Tesla chief executive Elon Musk is rolling his eyes over a secret new project by conservatives that's reportedly aimed at undermining the electric car market.

His tweet comes in response to a Huffington Post report suggesting that the billionaire Koch brothers want to kickstart a major lobbying effort to promote fossil fuels and criticize subsidies for electric vehicles. The lobbying group, which hasn't been announced, would likely spend $10 million a year, the report said.

The Obama administration has committed billions of dollars in grants toward electric car technology. Consumers can also receive a tax credit worth up to $7,500 if they buy an eligible electric car. These credits are designed to encourage adoption of the technology — and that threatens the Koch brothers' financial stake in oil and gas, according to the Huffington Post. Which just led Musk — who has bet big on electric cars in the Tesla Model S, Model X and the soon-to-be-announced Model 3 — to argue that the petroleum industry has also been a big beneficiary of government subsidies.

"Koch Industries does not oppose electric vehicles," said Philip Ellender, a spokesman for the company. "What we oppose is government subsidizing and mandating a particular form of energy over another. We oppose all subsidies – even for those industries in which we participate."

When billionaires go to war, the rest of us grab the popcorn.