For her part, Whitman said she was resigning because she was tired of a commuter marriage.
"It has been a singular honor to be entrusted with the responsibility to lead the EPA in its effort to leave America's air cleaner, its water purer, and its land better protected than it was when this administration took office," she wrote, adding that it was time for her "to return to my home and husband in New Jersey."
Candidates reported to be in line for her job include EPA Deputy Administrator Linda Fisher; Florida Environmental Protection Secretary David Struhs, the brother-in-law of Andrew Card, the White House chief of staff; Josephine Cooper, a former EPA official now with the Alliance of Automobile Manufacturers; and Tom Skinner, a regional EPA director and former Illinois state environmental director.