No matter who emerges as the Republican nominee, the party’s official policy will almost certainly take aim at the size, scope and structure of the E.P.A.
Conservative policy makers are considering proposals that would effectively strip the agency of its authority to set, put in place and enforce pollution standards. The agency would continue to exist, at least in name, but it could end up functioning only as a small scientific research agency, possibly swallowed into another department.
“There’s no reason to have the agency in its current form,” said Michael McKenna, a Republican energy lobbyist who has played a central role in drafting the party’s environmental policy platform in previous presidential campaigns. “Something’s going to be in the platform that gives the E.P.A. a serious haircut.”
Democratic candidates are not exactly rushing to the agency’s defense. Mrs. Clinton said that as president she would open an investigation into its handling of the Flint water crisis. Mr. Sanders said that he would “fire anybody who knew about what was happening and did not act appropriately.”
At Thursday’s hearing, Representative Tammy Duckworth, Democrat of Illinois and a highly regarded Senate candidate, said she was “extremely troubled by how the E.P.A. also failed in its duty to serve as the last line of defense for the children of Flint.”
The agency’s responsibilities have never been greater, and its resources have never been so strained.
Created in 1970 by President Richard M. Nixon, the E.P.A. is charged with writing, carrying out and enforcing regulations under existing laws like the Clean Air Act and the Clean Water Act. Its rules impose restrictions on business, industry and agriculture, limiting the amount and types of pollutants that can be emitted into the air and water, as well as where and how landowners can use their property. The regulations can sometimes impose billions of dollars of costs on industry, requiring companies to install expensive pollution control technology and in some cases to shut down polluting facilities.
But President Obama’s effort to combat global warming has transformed that mandate. The president’s climate policies require regulations so sweeping that the E.P.A. has essentially been tasked with transforming major sectors of the American economy, including the auto industry and the electric power sector, over the next decade.
Because those global warming regulations have been issued under the legal authority of an existing law, the Clean Air Act, it could be difficult for a Republican president to simply repeal them outright. But substantially weakening the agency that enacts the rules could effectively hamstring Mr. Obama’s climate change legacy.
Historically, environmental regulations have required polluters to install new equipment like so-called smokestack scrubbers and catalytic converters in cars, factories and power plants.
But Mr. Obama’s current suite of climate change regulations, if enacted, would go far beyond that. The E.P.A. would effectively change how automobiles are propelled (with electricity, not gasoline) and how electricity is delivered (via wind and solar, not coal), said Bob Persciacepe, the agency’s deputy administrator during Mr. Obama’s first term.
“We are at a pivotal moment in time, when, in fits and starts, the world is dealing with climate change and every country has to play an important role,” he said. “E.P.A. has been put in the spot to do this. The weight on their shoulders is heavy.”
All of this is supposed to be accomplished under tight budgets imposed by a hostile Congress. The agency’s spending under Mr. Obama has been cut between 10 and 20 percent below the budgets of the previous three administrations, when adjusted for inflation. The agency’s budget has averaged about $8.8 billion annually under Mr. Obama, compared with (in today’s dollars) $9.7 billion under George W. Bush, $10.6 billion under Bill Clinton and $10.4 billion under George Bush. The agency’s 15,408 employees are its fewest since 1989.
As the E.P.A. has taken on more work with fewer resources, problems have proliferated. Last year, after the E.P.A. accidentally spilled three million gallons of toxic wastewater from an abandoned mine into the Animas River in Colorado, a government report found that the agency lacked the technical skills to handle such tricky projects.
The agency has also been criticized for its implementation of a regulation known as “Waters of the U.S.,” which would expand pollution controls over the nation’s rivers and streams.
“It’s clear E.P.A. cannot currently handle the issues on its plate,” Representative Scott DesJarlais, Republican of Tennessee, said Thursday.
A spokeswoman for the E.P.A. declined to comment on the politics swirling around the agency. But Obama administration officials noted that the E.P.A. still enjoyed public support. A Pew poll in September 2015 found that 52 percent of respondents had a favorable view of the agency.
That support could make it more difficult for a Republican president to enact some of the most drastic changes envisioned by those drafting the party’s policy platform, because at least some proposals would have to go before Congress.
And eliminating the E.P.A. would not eliminate the government’s legal obligations to carry out regulations under existing laws.
“I’m a very conservative guy, and there are legitimate criticisms of E.P.A., and there has been E.P.A. overreach,” said Jeffrey Holmstead, a former deputy administrator of the agency under George W. Bush.
But, he noted, under the Clean Air Act and the Clean Water Act, the E.P.A. is required to supply operating permits to industrial plants and manufacturers.
“Even if E.P.A. disappeared tomorrow, the regulations would still have the force of law,” Mr. Holmstead said.
