A top climate change advocacy group on Friday dismissed presumptive Republican presidential nominee Donald Trump's selection of Rep. Kevin Cramer, R-N.D., to advise him on energy policy.

In a press release, NextGen Climate slammed Cramer, who they say represents Exxon Mobil thanks to large donations from the gas corporation, after it emerged that he would be advising Trump on energy. Cramer is a well-known advocate of fracking, having represented North Dakota, a major oil drilling state, since 2013.

"I was thrilled to read the news that Donald Trump has named you energy and climate advisor to his presidential campaign," the group wrote statement in letter format. "Given your close ties to the oil and gas industry, which has bankrolled your campaigns to the tune of more than half a million dollars, including $21,000 in PAC money from Exxon Mobil alone, I'm sure you know — as Exxon has since the 1970s — the role that carbon pollution plays in damaging our climate."

"It's apparent that Mr. Trump has a great deal to learn about climate and energy policy. We are fortunate he has chosen an advisor with such intimate knowledge of the damage continued reliance on dirty fossil fuels will do to our economy and to our families' health," the group said. "Please do not hesitate to reach out to me if you require more information about the economic benefits of transitioning to clean energy."

Earlier Friday, both Trump and Cramer pushed back against a report that the congressman was advising the presumptive nominee to endorse a carbon tax. Trump made his opposition known in a tweet sent out Friday afternoon, saying he will not back a tax of that sort.

"I would never encourage him or push him or even recommend him to initiate any type of a carbon tax," Cramer told The Hill in an interview.