Now, Waxman writes in a letter to the incoming committee chair, Fred Upton, it appears as if Michaels may have misled the committee. In 2009, Michaels said 3% of his $4.2m in financial support came from the oil and gas industry. But in an appearance on CNN in August last year, and in subsequent interviews, Michaels suggested that figure was 40%.
"Michaels may have provided misleading information about the sources of his funding and his ties to industries opposed to regulation of emissions responsible for climate change," Waxman writes in the letter, released on Monday.
Waxman urged Upton to call on Michaels to clarify the sources of his funding, and to give a complete account of his funding sources to the committee.
Michaels has also received direct funding from the Koch brothers. From their base in Wichita, Kansas, the Kochs control the largest privately held oil company in the US. They gained notoriety during the mid-term elections for bankrolling a leading, conservative Tea Party organisation, Americans for Prosperity.
But the Kochs have for years been funnelling money to organisations which oppose government regulations and deny the existence of climate change.