Former EPA Administrators have been critical of Pruitt's tenure. William Ruckelshaus, the first and fifth EPA Administrator under Richard Nixon and Ronald Reagan respectively, characterized Pruitt as disbelieving of "the mission of the agency" while believing that the EPA was "over-regulating". Ruckelshaus accused Pruitt of having an "ideological approach ... that affects the large contributors in his party in Oklahoma". Ruckelshaus also described the ideological opposition to the scientific consensus on climate change as a national "threat", and that "lives will be sacrificed" with further inaction. Ruckelshaus has also criticized Pruitt for lacking transparency.