**FILE** Environmental Protection Agency Administrator Lisa Jackson gestures during an interview April 17, 2012, with The Associated Press at the agency's Washington headquarters. (Associated Press)
**FILE** Environmental Protection Agency Administrator Lisa Jackson gestures during an interview April 17, 2012, with The Associated Press at the agency's Washington headquarters. (Associated Press)
**FILE** President Obama talks with Environmental Protection Agency Administrator Lisa Jackson on Jan. 10, 2012, at EPA headquarters. (Associated Press)
** FILE ** This photo April 17, 2012, file photo shows Environmental Protection Agency (EPA) Administrator Lisa Jackson during an interview with The Associated Press at EPA Headquarters in Washington. Jackson, The Obama administration's chief environmental watchdog, is stepping down after a nearly four-year tenure marked by high-profile brawls over global warming pollution, the Keystone XL oil pipeline, new controls on coal-fired plants and several other hot-button issues that affect the nation's economy and people's health. (AP Photo/Kevin Wolf, File)
** FILE ** This photo April 17, 2012, file photo shows Environmental Protection Agency (EPA) Administrator Lisa Jackson during an interview with The Associated Press at EPA Headquarters in Washington. Jackson, The Obama administration's chief environmental watchdog, is stepping down after a nearly four-year tenure marked by high-profile brawls over global warming pollution, the Keystone XL oil pipeline, new controls on coal-fired plants and several other hot-button issues that affect the nation's economy and people's health. (AP Photo/Kevin Wolf, File)
** FILE ** This photo April 17, 2012, file photo shows Environmental Protection Agency (EPA) Administrator Lisa Jackson during an interview with The Associated Press at EPA Headquarters in Washington. Jackson, The Obama administration's chief environmental watchdog, is stepping down after a nearly four-year tenure marked by high-profile brawls over global warming pollution, the Keystone XL oil pipeline, new controls on coal-fired plants and several other hot-button issues that affect the nation's economy and people's health. (AP Photo/Kevin Wolf, File)
** FILE ** In this April 17, 2012, file photo, Environmental Protection Agency (EPA) Administrator Lisa Jackson gestures during an interview with The Associated Press at EPA Headquarters in Washington. In its first major regulation since the election, the Obama administration will impose a new air quality standard that reduces by 20 percent the maximum amount of soot released into the air from smokestacks, diesel trucks and other sources of pollution. (AP Photo/Kevin Wolf, File)
**FILE** Environmental Protection Agency Administrator Lisa Jackson gestures during an interview April 17, 2012, with The Associated Press at the agency's Washington headquarters. (Associated Press)
** FILE ** This April 17, 2012, file photo shows Environmental Protection Agency (EPA) Administrator Lisa Jackson during an interview with The Associated Press at EPA Headquarters in Washington. (AP Photo/Kevin Wolf, File)
