Attorney General Scott Pruitt has sued the EPA at least 14 times to block pollution regulations and in all but one case, energy companies joining Pruitt in the lawsuits contributed to his campaign or to his PACs, according to a study by the Environmental Defense Fund.

The study, released Friday by the environmental group, reviewed state and federal campaign contribution records for Pruitt’s campaign and political action committees associated with him. The group found that in 13 out of 14 lawsuits Pruitt brought against the agency he hopes to lead, companies suing along with him had donated to his campaign or to PACs that support Pruitt.

“These co-litigators include some of the biggest polluters in the nation who stand to gain the most by blocking bedrock clean air and clean water safeguards,” states the release from the Environmental Defense Fund, a nonprofit group that bills itself as one of the world’s largest environmental organizations.

Pruitt’s office declined comment Friday on the study.

“The U. S. Senate Committee on Environment and Public Works has scheduled a bi-partisan hearing for next Wednesday and I encourage you to tune in for that,” Ferguson said.

Records show that in many instances, the companies joining Pruitt’s suits against the EPA  also contributed to the Republican Attorneys General Association.

The Environmental Defense Fund described the association as “an organization that Pruitt turned into a political powerhouse as past chairman, raising money from energy industry interests at the same time he submitted their comments to EPA, nearly word for word, on Attorney General letterhead.”

“We already know Pruitt is a staunch opponent of safeguards that protect all Americans from mercury, arsenic and smog pollution – but we are learning more every day about his tight alliance with polluting industries.”

[Read the list of Pruitt’s lawsuits against the EPA, including links to companies and organizations that joined his lawsuits and contributed to his campaign or PACs supporting him.]

Pruitt has been nominated by President-elect Donald Trump to lead the U.S. Environmental Protection Agency, which is responsible for enforcing the nation’s environmental laws protecting land, air and water. The Senate Environment and Public Works has scheduled Pruitt’s confirmation hearing Wednesday at 9 a.m. CST.

Sen. John Barrasso (R-WY), chairman of the committee, said in a release: “Attorney General Pruitt’s confirmation hearing will be an opportunity to hear his vision for the agency. It will give senators the chance to ask questions and to hear Mr. Pruitt’s plans on how to help the EPA meet its mission of protecting the environment while strengthening the economy.”

Sen. Barbara Boxer, the ranking minority member, has opposed Pruitt’s nomination: “President-elect Trump has selected someone who, as Oklahoma Attorney General, has fought on the side of big polluters and special interests over the health of the people of his state,” she said in a news release.

“He has sued the EPA to overturn common-sense public health protections, and he stands with climate deniers. There can be no doubt that Mr. Pruitt is the wrong choice because he will continue to try to roll back our landmark environmental laws like the Clean Air Act and the Clean Water Act, and that is disastrous for the American people.”

Pruitt has kept a low profile since his nomination became public. (He has not responded to interview requests from The Frontier.) However, he hasn’t been reluctant to make clear his disdain for the agency he hopes to lead.

“EPA’s War On America’s Energy Producers Needs to END,” he wrote in a 2014 Facebook post.I am troubled by the Obama administration’s direct and indirect attempts to discourage domestic energy production and am prepared to challenge these attacks when needed.”

The Environmental Defense Fund found that Pruitt’s campaign has accepted about $350,000 from energy-related interests during his political career.

Soon after taking office, Pruitt closed the agency’s environmental enforcement division and created a federalist division devoted “in large part to suing EPA and blocking common-sense safeguards for clean air and clean water,” the release states.

An investigation by The Frontier found that Pruitt did not abide by a state law that requires state agency disclosure of spending on outside attorneys. The law requires the attorney general to compile a report showing spending and contract details for each agency with outside legal counsel.

The Frontier’s investigation found that Pruitt has spent more than $1 million since FY 2012 on legal fees but did not disclose that spending in the reports he prepared. That total does not include attorneys’ fees and costs spent on Pruitt’s suits against the EPA or to challenge the Affordable Care Act.

His office has said a partner in a Wasington D.C. law firm handled the lawsuits without charge to the state. However, Pruitt has not responded to The Frontier’s requests to clarify whether any outside entity paid for the firm’s work in the cases.

Here’s a list compiled by the Environmental Defense Fund of the 14 major lawsuits Pruitt has filed against the EPA, with links to contributions from energy companies and associations joining the lawsuits.