Mr. Ebell’s C.E.I. and other groups have previously received funding from the fuel-manufacturers’ organization, though as a nonprofit, the C.E.I. is not required under law to disclose its donors, making it difficult to verify current funding.
Last month, Congress opened an investigation into petroleum companies’ involvement in the rollback.
The latest emails also show Trump administration officials in contact with other free market groups like the Heritage Foundation and FreedomWorks, both of which have supported the rollback, as well as the American Legislative Exchange Council, an organization run by mostly Republican state legislators and corporations that work together to write and promote model legislation for the nation’s statehouses.
In one email, in June 2018, an ALEC staffer wrote to Michael Abboud, the E.P.A. press secretary, to introduce him to the head of ALEC’s task force on energy, environment and agriculture, Grant Kidwell. Mr. Kidwell “would love the connection to the EPA,” the staffer wrote.
“Thanks for the introduction!,” Mr. Abboud responded. “I would love to get together for coffee and chat?” ALEC, which has said it welcomes debate among its members on climate change and has promoted policies that would lead to more emissions, later adopted a model resolution that “fully supports” a rethinking of the fuel economy standards.
Mr. Kidwell said he and Mr. Abboud did not interact until they ran into each other at a networking event this year. ALEC opposed the Obama-era fuel economy standards, Mr. Kidwell said, because “Americans should be able to buy vehicles they prefer.”
Mr. Abboud declined to comment specifically on the email. The “E.P.A. takes time to meet with stakeholders on a variety of regulatory issues,” he said in an agency statement. “This is no different.”
The denialists’ outreach to the administration has taken other forms. American Commitment, another conservative group, helped generate almost 1,600 public comments in support of the rollback, or 13 percent of the 12,000 comments received and posted by the National Highway Traffic Safety Administration.