Sen. Susan Collins (R-ME) announced that she will oppose the nomination of Oklahoma Attorney General Scott Pruitt to serve as administrator to the U.S. Environmental Protection Agency.

“Due to my concerns about Mr. Pruitt’s commitment to the mission of the EPA, I will cast my vote in opposition to his confirmation,” Collins said in a statement.

“The fact is, Mr. Pruitt and I have fundamentally different views of the role and mission of the EPA,” her statement said. “That does not mean that I agree with every regulatory action that EPA has taken… but the EPA plays a vital role in implementing and enforcing landmark laws that protect not only our environment but also public health.” Collins specifically cited Pruitt’s opposition to “numerous issues that are of great importance to the state of Maine, including mercury controls for coal-fired power plants and efforts to reduce cross-state air pollution and greenhouse gas emissions.” Pruitt has cast doubts on the viability of climate science.

Collins said Pruitt’s past action leave her “with considerable doubts about whether his vision for the EPA is consistent with the Agency’s critical mission to protect human health and the environment.” The final vote on his nomination is expected to come on Friday.