Two sources within the Environmental Protection Agency have told government watchdog groups that the Obama administration interfered with investigations of hydraulic fracturing during the 2012 presidential campaign.

The American Traditional Institute (ATI) and the Free Market Environmental Law Clinic (FMELC) filed two Freedom of Information Act requests after receiving tips from two separate career EPA employees who charged that politics drove the EPA’s handling of a fracking study in Pennsylvania.

“These two EPA employees appear credible; one we have established is quite reliable and the other was referred to us by a highly-regarded and well-known academic scientist,” said Chris Horner, ATI senior fellow and FMELC attorney, who filed the FOIA requests.