There was no shortage of suspects in the case of who killed the nomination yesterday of Chuck Hurley to be the new administrator of the National Highway Traffic Safety Administration. But environmental advocates - and not the carmakers or the alcohol industry - appear to be the culprit, sources tell National Journal.

Hurley, most recently the head of Mothers Against Drunk Driving, abruptly withdrew his name Tuesday, before the nomination had even been made official. While a wide array of stakeholders had expressed nervousness about aspects of Hurley's record since his appointment was announced in April, Hurley's sudden withdrawal caught insiders on all sides by surprise.

An administration official said he knew nothing beyond confirming that Hurley had withdrawn. But a source who spoke to Hurley said the former nominee cited environmentalists' concerns that he was too soft on raising Corporate Average Fuel Economy standards - the fuel efficiency requirements that NHTSA imposes on carmakers.

"He said he withdrew because he was getting opposition from the environmental community, who did not like his previous statements about the impact of raising the CAFE standards on safety," the source said.

Since his appointment, environmental advocates had expressed concern about statements made when Hurley worked for the Insurance Institute for Highway Safety. Hurley had suggested that changes in car design in response to rising CAFE standards, such as making cars smaller and lighter, were dangerous for drivers and passengers who were involved in a crash.

Environmental groups reject the notion of a zero-sum tradeoff. "I was surprised to hear he had withdrawn, but it's good to know that people are listening on fuel economy and safety," said Lena Pons, a policy analyst at Public Citizen.