Chevron, the second-largest oil company in the U.S. and eighth-largest in the world, contributed $2.5 million in October to the Congressional Leadership Fund, a super PAC to elect House Republicans. That makes Chevron’s super PAC donation the single largest from a corporation.

The donation comes after House Republicans voted 109 times this Congress to enrich oil companies. According to Public Campaign Action Fund’s Adam Smith:

The donation appears to be the largest from a publicly-traded corporation in the post-Citizens United era. The corporate donation is double what the company’s PAC and employees have already donated to federal candidates and committees this cycle, according to analysis of data from the Center for Responsive Politics.

The company’s donation arrives in an election year where the oil industry has waged multimillion-dollar ad campaigns, including American Petroleum Institute’s campaign in swing states. Chevron has also sent 91 percent of its federal political contributions to Republican candidates. So far this year, fossil fuel groups have spent more than $153 million on campaign ads to promote pro-fossil fuel candidates.

Chevron gets a good return for its loyalty. House Republicans voted at least twice to protect Big Oil’s $2.4 billion in taxpayer subsidies. Chevron alone receives an estimated $700 million in annual tax breaks. And the company spent $16.6 million of Big Oil’s $105 million lobbying Congress to block pollution controls and safeguards for public health.