Administrator of the Environmental Protection Agency Lisa Jackson, who for four years had led the charge on a number of successful moves to increase and strengthen environmental regulations, has announced that she is stepping down from the agency, reported The Hill.

Jackson, who will officially leave soon after President Obama's State of the Union address, announced no particular plans but said in a statement that she looks forward to "new challenges, time with my family and new opportunities to make a difference."

Jackson headed the agency as it imposed the first greenhouse gas standards for vehicles, created new limits on soot emissions, went to court for the Clean Air Act, and passed regulations on new power plants.

However, some who believed President Obama would aggressively pursue all-encompassing climate change legislation frame those successes as consolation prizes. As a result, Jackson faced opposition and setbacks not only from Republicans who generally oppose increased regulations, but from Obama himself, as well as environmental groups who grew frustrated when the agency compromised to move its agenda, reported the New York Times.

In 2011, Obama buckled to opposition groups and prevented the EPA from implemented more stringent air quality standards. Environmental groups also want the president to impose new regulations on power plants that already exist, reported the Washington Post.

Republicans frustrated with those new rules claim that they hamper business and have attempted to pass legislation to limit the agency's power.

In a statement, Jackson, the first African American to lead the EPA, thanked President Obama for appointing her in 2008: “At the time I spoke about the need to address climate change, but also said: 'There is much more on the agenda: air pollution, toxic chemicals and children’s health issues, redevelopment and waste-site cleanup issues, and justice for the communities who bear disproportionate risk.'"

Jackson, a New Orleans native whose mother was a postal worker, used her personal life to explain her policy decisions, specifically referencing her son's asthma when fighting for regulations on air pollution.

Since her announcement, there has also been speculation that she will run for governor of New Jersey, where she headed the state's Department of Environmental Protection before taking the EPA post, reported

[Image: Chesapeake Bay Program on Flickr, Creative Commons licensed]