Green groups cheered the resignation Thursday of Scott Pruitt, saying the Environmental Protection Agency administrator’s multiple ethical lapses and pro-polluter tilt made him unsuitable for the nation’s highest environmental post.

But the activists doubted that the departure, announced by President Trump via Twitter, would change the administration's policies. The EPA will now be led by an interim chief, Andrew Wheeler, who was a coal industry lobbyist before he was confirmed as Pruitt's deputy in April.

Pruitt’s tenure was marked by more than a dozen investigations into alleged conflicts of interest and controversial spending of taxpayer funds — ranging from his use of an outsized security detail, to his scheduling of numerous expensive foreign trips, to his acceptance of what appeared to be a below-market condominium rental connected to a lobbyist.

Pruitt's time at the helm of the EPA was also defined by an aggressive push to undo President Barack Obama's environmental legacy. He took aim at Obama-era regulations that sought to curb toxic pollution and carbon emissions, expressed doubt about climate science, and even championed fossil fuels and coal — moves that troubled environmentalists.

Ken Cook, president of the Environmental Working Group, deemed Pruitt "the worst head of the agency in its 48-year history."

"He will forever be associated with extraordinary ethical corruption and the abuse of power for petty personal enrichments," Cook said in a statement. "Sadly, the ideological fervor with which Pruitt pursued the destruction of environmental regulations and the agency itself live on in the Trump administration."

The Sierra Club seconded the notion that Pruitt was the worst EPA boss ever. The group's executive director, Michael Brune, added of Trump: "Any president that cared about protecting taxpayers, respecting science, tackling the climate crisis, or protecting the environment would have fired him months ago. "

Rhea Suh, president of the Natural Resources Defense Council, also bashed the outgoing official.

"Ethics matter. So does a commitment to EPA’s central mission," Suh said in a statement. "Pruitt failed miserably on both counts. If his successor also puts the interests of polluters ahead of protecting public health, he or she will encounter the same wall of resistance — and meet the same fate."

A spokesperson for the EPA did not immediately respond to a request for comment.

Trump has for months stood by Pruitt, a former Oklahoma attorney general. The president said as recently as June that the EPA chief was "doing really, really well."

But environmental groups chafed at Pruitt’s actions, particularly his support of fossil fuel industries, like coal. Scientists have reached a consensus that the burning of fossil fuels is a major creator of so-called greenhouse gases, like carbon dioxide, that are warming the Earth and setting the stage for a cascading set of other challenges, like rising sea levels, droughts and wildfires.

The environmental groups said they don’t expect Pruitt’s departure to mark a change in direction.

His replacement as interim director will be Wheeler, who was confirmed by the Senate in April to the EPA’s No. 2 post. The vote was 53-45.

Andrew Wheeler. EPA via AP

Wheeler once served as chief of staff to Oklahoma Sen. James Inhofe, perhaps the most vocal denier of climate change in Congress. The senator told NBC News recently that he talks to Wheeler almost daily.

After leaving his duties in the Senate, Wheeler worked for a law firm that lobbied for the coal industry. His biggest client was Murray Energy Corp., the largest coal mining company in America, according to the Natural Resources Defense Council. Murray’s CEO, Robert E. Murray, "vigorously fought the Obama administration’s attempts to reduce carbon emissions and strengthen environmental and public health laws," according to an analysis by the environmental group.

The group's report said that Wheeler also served as a vice president of a 300-strong federation of coal interests in the capital called the Washington Coal Club and "made time to lobby the U.S. Department of the Interior to open portions of the Bears Ears National Monument to uranium mining."

The Natural Resources Defense Council statement called Wheeler "unqualified" and said it would fight his "pollution agenda with the same vigor as we did Pruitt’s."

In his tweet announcing the resignation, Trump thanked Pruitt was his "outstanding job." The president signaled no change of direction with the elevation of Wheeler, saying: "I have no doubt that Andy will continue on with our great and lasting EPA agenda. We have made tremendous progress and the future of the EPA is very bright!"