Wisconsin Democratic Sen. Tammy Baldwin says she'll vote against President Donald Trump's nomination to head the U.S. Environmental Protection Agency, Oklahoma Attorney General Scott Pruitt.

Baldwin said Pruitt "would turn back the clock and dismantle much, if not all, of the progress made on clean air, clean water and protecting our environment."

Baldwin's statement comes as about 20 Wisconsin scientists, who are members of the National Academy of Sciences, have issued a letter urging both of Wisconsin's U.S. senators to reject Pruitt.

Republican Sen. Ron Johnson has yet to say how he'll vote.

University of Wisconsin-Madison biochemistry and chemistry professor Laura Kiessling, who co-wrote the letter, said Pruitt's skepticism about climate change could affect EPA's willingness to protect the quality of life in Wisconsin.

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"Like loss of walleye habitat, you know, inability to snowmobile, which is an issue right now for many people in the state," Kiessling said, noting most of the signers work at the university.

She said she hopes they, as public employees, don't face repercussions for speaking out.

"I would hate to see that prevent us from sharing views on issues that are important as this one, " Kiessling said.

The Republican chairman of the Senate Environment and Public Works Committee has said Pruitt is qualified to lead the EPA.

According to the Wisconsin Republican Party, Baldwin’s opposition to Pruitt puts her in lock-step with an Obama administration water rule that conservatives say would expand regulatory powers to unreasonable levels at the expense of Wisconsin farmers.