Emails obtained by the Sierra Club, as part of a lawsuit filed against the EPA, show numerous communications between Pruitt's chief of staff, Ryan Jackson, and lobbyist J. Steven Hart, in which it appears Hart tried to guide and influence EPA decisions -– efforts Hart and Pruitt had earlier denied.
Hart sent some emails while the administrator was renting the condo from his wife.
“These emails make clear that Scott Pruitt got a sweetheart deal from a lobbyist with business before the EPA and then blatantly lied to the American people about it,” said Michael Brune, the executive director of the Sierra Club.
The emails between Jackson, Pruitt’s senior-most advisor, and Hart, who at the time was a senior attorney at Williams Jensen, a powerhouse Washington lobbying firm, come frequently and show a close relationship. Hart invites Jackson out for dinner and often asks him for favors -- including trying to get friends employed at the EPA.
Hart sent an email to Jackson in April 2017 about a family friend who had applied for a job at the EPA. Jimmy Guiliano was seeking a policy position at the EPA when Hart wrote to Jackson that his wife, Pruitt's landlord, spoke to Pruitt directly and he was following up on the matter.
"He [Pruitt] told Vicki to talk to you about how to handle this," Hart writes Jackson.
Jackson responds "on it" after Hart wrote that Guliano was "important to us." In a statement to ABC News, EPA spokesman Jahan Wilcox said "the Agency accepts career recommendations from a number of acquaintances. Ultimately, Mr. Guiliano was not hired."
In another email exchange from June 2017, Hart emails Jackson the biography of Dennis Treacy, the president of the Smithfield Foundation -- the charitable arm of Smithfield Foods, which is a company Hart was representing.
Hart writes in the body of the email: "He is a Virginia rep on the Chesapeake Bay and a conservative R. He is controllable."
In a follow-up, Hart writes to Jackson later that same day: "Pruitt is already scheduled to meet with Dennis on July 11 with me along. Dennis is controllable so do not default on this one."
The lobbyist goes on to talk about other plans they have and then asks Jackson to call him.
"No urgency but we need to talk about issues unrelated to the EPA."
It's unclear what that may be referring to.
A spokesman for Smithfield "these activities were not undertaken" at the company's direction, but rather in requests by Treacy, who they said was associated with "a number of other environmental organizations."
"Smithfield expects its advisors to comply with all applicable laws including those requiring timely public disclosure of lobbying activities," the spokesman said in a statement to ABC News.
Meanwhile, Hart said the condo arrangement had no bearing on his contacts with the E.P.A.
"As I have said repeatedly, I never received any special treatment from Administrator Pruitt or had any undue influence over the Environmental Protection Agency," he said in a statement to ABC News. "Ryan Jackson is an old friend whom I have known for many years prior to his service with the EPA. We have discussed numerous issues and topics during his tenure as chief of staff, but he has never performed a special favor on my behalf."
Hart's emails continued on a wide array of topics. In one email late last year, Hart wrote to Jackson about the fledgling nomination of Michael Dourson to oversee the EPA's chemical safety division.
"Having dinner with Burr tonight," Hart tells Jackson in the November 2017 email, referring to Senator Richard Burr. "Should I try to move him or want to just give up?"
Dourson's nomination was eventually pulled the next month by the Trump Administration.
“A president with any shame whatsoever would have fired him months ago,” he said, referring to President Trump.
"Ryan Jackson and Mr. Hart are both from Oklahoma and have known each other for years," Wilcox told ABC News on behalf of the EPA. "Many of these emails were unsolicited and did not impact any Agency policy outcomes."
Separately, an investigation from the EPA’s inspector general revealed that Pruitt’s chief of staff, Jackson, directly oversaw and approved the pay raises for two of Pruitt's longest-serving aides: Sarah Greenwalt and Millan Hupp.
Greenwalt received a raise of more than $50,000, which brought her salary to more than $164,000. And a nearly $30,000 raise was approved for Hupp, which brought her salary to more than $114,000.
Shortly after the raises became public, Pruitt told Fox News in an interview that he didn't know anything about the raises and that he had taken action to reverse them. But Pruitt later told a congressional committee that he gave a top aide permission to give at least two EPA employees big raises, deviating from how he characterized authorization for these raises in the past.
Both aides have since resigned.
Members of Congress on both sides of the aisle have grown frustrated with Pruitt. Iowa Senator Joni Ernst said earlier this month Pruitt "is about as swampy as you get here in Washington, D.C. And, if the President wants to drain the swamp he needs to take a look at his own cabinet."
Pruitt's former communications aide, Liz Bowman, resigned her position at the EPA and now works for Ernst, who is leading a charge to remove Pruitt complete with flashy television ads.
For his part, President Trump is standing with Pruitt.
“I’m looking at Scott, and Scott’s done a fantastic job at EPA,” Trump told reporters earlier this month when asked about the growing questions. “I’m not happy about certain things. I’ll be honest.”
Senior White House sources do not believe the president has any current intentions of dismissing Pruitt.
ABC News' Katherine Faulders contributed to this report.