While she charmed some of her critics — Sen. James M. Inhofe (R-Okla.) referred to Jackson as “my favorite bureaucrat” — she alienated much of the business community. Ross Eisenberg, vice president for energy and resources policy at the National Association of Manufacturers, complained to reporters recently that Jackson and her deputies consistently failed to achieve a balance when regulating pollutants from industrial activities.

“EPA seems wedded to the notion that it must push its policies as hard as it possibly can, with the goal being to enact the strictest possible standard that will survive legal scrutiny,” Eisenberg said. “That’s not EPA’s job.”

Scott Segal, a partner at the law firm Bracewell & Giuliani who represents coal-fired utilities as director of the Electric Reliability Coordinating Council, wrote in an e-mail that Jackson managed to drive environmental policy in Washington because of “her excellent communications skills, likable personality and skilled use of political leverage.”

But Segal also criticized her for enacting costly regulations and misleading the public by exaggerating their benefits: “Agency rules have been used as blunt attempts to marginalize coal and other solid fossil fuels and to make motor fuels more costly at the expense of industrial jobs, energy security and economic recovery.”

Jackson said in an interview that she is open to pursuing consulting and public speaking and misses New Jersey, which is where she and her family lived before moving to Washington in 2009. Her name has been floated as a possible candidate for the presidency of Princeton University, where she received a graduate degree in engineering.