WASHINGTON — The Senate on Thursday confirmed the Environmental Protection Agency’s second-in-command, Andrew Wheeler, a former coal lobbyist who not only shares the deregulatory zeal of Scott Pruitt, the E.P.A. chief, but also his doubtful view of climate science.

More notable, however, are the differences between the two men.

Unlike Mr. Pruitt, a Washington outsider caught in a swirl of controversy over his costly first-class travel and security spending, Mr. Wheeler is viewed as a low-key insider with years of Washington experience in the art of pursuing policy change while avoiding public distraction.

Deregulation is among President Trump’s central campaign promises, and Mr. Pruitt has proposed ambitious rollbacks of rules governing clean air and water and fighting against climate change. But many of his initiatives have stumbled because of haste or imprecision, and at least six have been struck down by the courts. That makes the arrival of Mr. Wheeler’s expertise particularly consequential.

In fact, on Thursday Mr. Trump also sent new marching orders to the E.P.A., directing the agency to weaken or delay implementation of a variety of air pollution regulations, several of which have been priorities for industries for which Mr. Wheeler has lobbied in the past.