Mr. Wheeler, on the other hand, has led the professional life of a technocrat, avoiding the limelight in favor of carefully advancing his boss’s agenda. Both his supporters and critics say Mr. Wheeler’s history as a coal lobbyist, former E.P.A. official and senior Senate staffer could make him far more formidable at effectively advancing Mr. Trump’s deregulation policies, while avoiding the political spotlight or ethical pitfalls that derailed his predecessor.

“I would say he’s been absolutely as relentless and faithful to the agenda as Pruitt was,” said Joseph Goffman, who previously served as chief counsel to E.P.A.’s air chief in the Obama administration.

Mr. Wheeler began his career at the E.P.A. in the 1990s before working in the Senate for more than a decade with James Inhofe, Republican of Oklahoma. Senator Inhofe is one of the most prominent members of Congress who denies the established science of human-caused climate change.

Mr. Wheeler later became a lobbyist at the Faegre Baker Daniels consulting firm, where his top client was the coal magnate Robert E. Murray, chief executive of the Murray Energy. Over a period of eight years, Mr. Murray paid Mr. Wheeler’s firm more than $2.7 million.

Mr. Murray, a champion of the coal industry and a strong supporter of Mr. Trump, lobbied senior officials at the White House last year with a wish list of actions he wanted to see the administration take. The items included withdrawing to the Paris climate agreement and rolling back Mr. Obama’s signature climate change regulation, the Clean Power Plan, which was designed to reduce planet-warming emissions from coal plants and encourage renewable energy.

During Mr. Wheeler’s confirmation hearing to be E.P.A. deputy administrator, and later when he became acting administrator, he acknowledged working with Mr. Murray to fight the Clean Power Plan. But he said he had no substantive involvement with the memos that Mr. Murray wrote outlining his regulatory wish list. Mr. Wheeler also said he did not lobby E.P.A. on Mr. Murray’s behalf after the 2016 election, knowing he might join the Trump administration.

Senator Inhofe said this week that, should Mr. Wheeler be nominated to lead the agency, he would expect the confirmation to be straightforward. “I know there is no opposition to him,” the senator said. “He is of course the favorite of the president, and of mine.”