The Senate on Wednesday voted to confirm Lee Zeldin to run the Environmental Protection Agency, where he will be charged with executing President Trump’s orders to dismantle major environmental regulations, and possibly parts of the 55-year-old agency itself.

The Senate voted 56 to 42 to confirm Mr. Zeldin, a former House member with little experience in environmental regulation. He is expected to work to erase rules to fight climate change and chemical pollution, while shutting down programs designed to help poor and minority communities that are disproportionately affected by pollution.

In his Senate confirmation hearing on Jan. 16, Mr. Zeldin told lawmakers that he would “enthusiastically uphold” the agency’s mission to protect human health and the environment, and that he grasped the basic science of climate change.

“I strongly believe we have a moral responsibility to be good stewards of our environment for generations to come,” he said.

But Mr. Zeldin has also been directed to dismantle the largest climate rule ever enacted by the federal government. The rule, finalized last year, would cut tailpipe emissions of greenhouse gases, the nation’s largest source of planet-warming pollution, by compelling automakers to increase sales of hybrid and all-electric vehicles.

Mr. Trump incorrectly refers to the rule as the “EV mandate”; the rule does not ban gas-powered vehicles.

“Lee Zeldin will continue President Trump’s mission to roll back punishing, political regulations,” said Senator John Barrasso of Wyoming, a member of the Republican leadership, on the Senate floor ahead of the confirmation vote.

But at his confirmation hearing, Mr. Zeldin would not say how he intends to handle the tailpipe regulation, telling senators, “I am not allowed to prejudge the outcomes going into rule-making.”

However, Sean Duffy, the new transportation secretary, released a memo just hours after he was confirmed announcing plans to weaken auto fuel economy standards, which are a companion to the E.P.A. emissions limits. Under the Biden administration, the pair of rules worked in tandem to reduce pollution and were both aimed at the same goal of ensuring that more than half of new passenger vehicles sold in the United States are all-electric by 2032.

The American Petroleum Institute, which represents large oil companies, sought the elimination of both rules.

In the weeks since Mr. Trump won the presidential election, auto companies asked him to maintain some form of the Biden rules although with some adjustments, such as lowered penalties for noncompliance. While they have chafed at the requirements to rapidly increase sales of electric vehicles, automakers have also invested billions to transition to E.V.s.

Automakers fear that if the rules are erased, they could be undercut by companies selling cheaper, gas-powered cars. They are also concerned that it could hurt American competitiveness with China, home to the world’s largest E.V. manufacturer, and hurt an industry that is a backbone of American manufacturing and employs 1.1 million people.

But John Bozzella, president of the Alliance for Automotive Innovation, which represents manufacturers of nearly all the new vehicles sold in the United States, said on Wednesday, “It’s reasonable for the new leadership at the Transportation Department to review current fuel economy standards.”

Drew Kodjak, an expert in vehicle technology and policy who served in the Biden White House pointed out that revising the tailpipe emissions limits requires a legal process that takes years.

Additionally, the E.P.A. under Mr. Zeldin is also expected to try to revoke California’s legal authority to set tailpipe limits that are stricter than the national standard. The state now requires that all new cars sold there must be zero-emissions by 2035 and more than a dozen other states have adopted the same rule.

Also on Tuesday, Jim Payne, the E.P.A.’s acting administrator, announced that all members of two of the agency’s major scientific advisory panels, the Scientific Advisory Board and the Clean Air Scientific Advisory Committee, will be dismissed, though members will be allowed to reapply.

The move has echoes of steps taken in both the previous Trump administration and the Biden administration, as the role of scientists in shaping environmental policy became a political target. During the first Trump administration, in a then-unprecedented move, several academic scientists were dismissed from another E.P.A. panel, the Board of Science Counselors, and from the Clean Air Scientific Advisory Committee. The Trump administration said that any scientist on those panels whose research received funding by E.P.A. grants could not weigh in objectively on E.P.A. regulations. The first Trump administration also disbanded another scientific board, the Particulate Matter Review Panel.

In some cases, the administration replaced those scientists with representatives of polluting industries that the E.P.A. regulates. At the beginning of the Biden administration, E.P.A. administrator Michael S. Regan fired members of the Scientific Integrity Board and the Clean Air Scientific Advisory Committee and appointed new advisers.

Joseph Arvai, an oceanographer and psychologist who served on the E.P.A.’s scientific advisory board from 2011 to 2017 and again from 2021 until he was fired on Tuesday, said that he does not intend to reapply for the position.

He recalled being fired along with other scientists by the first Trump administration. “In 2017, it felt like there was no plan, it was just intended to freak people out,” he said. “Now it feels like there’s a plan.”