WASHINGTON (AP) — A plan by President Donald Trump's administration to slash the Environmental Protection Agency's budget by half has been the focus of contentious congressional hearings over the future of an agency that Democrats have accused of abandoning its mission to protect the environment and public health.

The Senate Environment hearing is expected to start at 2:30 p.m. EDT. Watch live in our video player above.

EPA Administrator Lee Zeldin will sit before a Senate committee Wednesday, the last of three budgetary hearings this week, to argue for sharply reduced funding for an agency that has already seen its staffing reduced to its lowest level in decades under his leadership. He took an aggressive approach, responding to Democratic lawmakers with his own questions and at times accusing them of being unprepared or failing to care about the agency's track record.

Zeldin has eliminated major climate change programs, promoted deregulatory efforts he calls the biggest in American history and canceled billions of dollars in Biden-era environmental justice grants to halt what he calls "EPA's radical diversity, equity, and inclusion programs."

The Republican administration's proposed $4.2 billion EPA budget would sharply reduce support for state environmental programs and state-administered loans for water projects. It also would halt what it calls "radical climate research" and slash resources for enforcement and compliance. Officials also asked for more money for faster project permitting and to address drinking water disasters.

Zeldin aggressively responded to questioning from Democrats

Congress gets final say, which commonly departs from White House requests. Last year, lawmakers rejected most of Trump's proposed cuts, reducing agency spending by just 3.5% despite an administration request to cut spending by more than half. Democrats said the budget plan shows that Zeldin is a friend to industry and ignores the cancers, asthma and other consequences of pollution.

"The budget proposal reads like a climate change deniers' manifesto," said Connecticut Rep. Rosa DeLauro, the top Democrat on the House Appropriations Committee. At a hearing Monday, she asked how the EPA can justify abandoning its duty to protect Americans "under the false flag of economic growth?"

The EPA has proposed rescinding a landmark finding that climate change is dangerous, loosened Biden-era rules limiting pollution from coal plants and proposed scrapping greenhouse gas emission limits for certain vehicles.

In response to DeLauro, Zeldin asked where the Clean Air Act mentions fighting climate change and whether she had heard of a recent Supreme Court decision that restricted the EPA's authority to write aggressive regulations.

"You do not have the right to say climate change does not exist, that it's a hoax," DeLauro said.

Zeldin said that he understood she was upset and that she should know about major Supreme Court decisions. "You're just somebody who likes to have the microphone on," he said.

It devolved from there. DeLauro said that the Trump administration's behavior is "arrogant" and that it was "making a mockery of what the agencies are all about."

Zeldin told California Democratic Rep. Josh Harder that data he cited on the agency's rollback of certain coal plant emissions limits was worthless — "Have your dog pee on it. It is not accurate." Harder's office later provided the EPA report that it said the numbers came from.

Zeldin's vision for the EPA

Zeldin argued that even with less money, the agency has continued to enforce environmental laws and achieved significant wins: an agreement with Mexico to reduce sewage flows into the heavily polluted Tijuana River and sped-up work to address radioactive contamination in the St. Louis region, as examples.

That work complements strict adherence to the law, a departure from what Zeldin says was the regulatory overreach of President Joe Biden's Democratic administration that wanted to strangle vital industries such as coal.

Republicans were largely supportive of Zeldin's message that, "Not only will we be able to fulfill all of our statutory obligations, we will be able to do more with less."

The 2021 bipartisan infrastructure law provided tens of billions of dollars for drinking and wastewater loans through programs administered by states. That boost, however, ends this year, and the EPA's proposed budget would cut off most of the agency's support.

"It was never intended to be a new norm for spending," said Virginia Republican Rep. Morgan Griffith.

But that would choke off money to remove harmful PFAS from drinking water. The agency's contention that better technology could do the job for less was unpersuasive, according to Democratic Rep. Jake Auchincloss of Massachusetts.

"How do we get rid of PFAS in municipal water supplies with 90% fewer dollars?" he asked.

Zeldin responded that technologies were promising and then mentioned congressional earmarks, which members have used to fund projects in their districts with money that would otherwise go to states for loans — a practice many experts have criticized.

"I know that members of Congress are going to raid it, and they have been doing it for a long time," said Zeldin, a former New York congressman.

Auchincloss replied that Zeldin wasn't in charge of earmarks and that "hope is not a strategy."

Zeldin was also questioned about industry influence on policymaking, with a particular focus on the Make America Healthy Again movement, which has attacked environmental harms from products like fertilizer. The movement's biggest champion is Health Secretary Robert F. Kennedy Jr.

Maine Democratic Rep. Chellie Pingree asked Zeldin whether he understood concerns from those advocates about industry influence at the EPA and the Trump administration's support of more pesticides.

He called much of the lengthy question inaccurate and then mentioned plans to look at microplastics as a potential contaminant in drinking water and an upcoming review of the high-profile herbicide glyphosate.

"I get it, you have an agenda," Zeldin said. "I mean, I understand you'd like to have a gavel in your hand."

Associated Press writer Matthew Daly contributed to this report.