puts Hamm at number 36 on their list of billionaires in the United States. Earlier this year, he complained to Businessweek that he had not gotten enough attention from President Barack Obama during a White House meeting last year.

"It was like, if you’re in the oil-and-gas industry, you don’t matter," he recalled.

Last October, he gave the maximum contribution of $2,500 directly to Mitt Romney's campaign and on April 3 he donated $985,000 to Restore Our Future, a pro-Romney super PAC.

On March 1, the Romney campaign announced that Hamm had been named as the chairman of their "Energy Policy Advisory Group."

Hamm has since slammed Obama's energy policy as a failure, even though the Wall Street Journal reported that "almost all" of his wealth was generated during the president's first term.