Oklahoma Attorney General Scott Pruitt may be a climate change denier, but that alone won’t derail his nomination to lead the Environmental Protection Agency. So when confirmation hearings for President-elect Donald Trump’s controversial pick begin on January 18, you can expect to hear a lot about mercury. It’s part of a larger strategy by Senate Democrats to frame his nomination as the culmination of a cynical, years-long attack on science and reason whose purpose was to protect the interests of the fossil fuel industry—and his own.

Opposing mercury pollution is a no-brainer. Its harms include serious damage to the nervous, pulmonary, digestive, and immune systems and developmental brain defects. In 2011, after years of study, the EPA limited how much mercury oil-fired and coal-fired power plants can emit. The agency’s Mercury and Toxic Air Standards (MATS) will save thousands of lives and prevent an estimated 11,000 premature births a year. Great, right? Not according to Pruitt, who joined more than 20 states in suing to block the rule—an appeal that was ultimately declined by the Supreme Court last summer, leaving the rule in place.

For Senator Tom Carper of Delaware, the Democrats’ ranking member on the Senate Environment and Public Works (EPW) Committee, mercury is a great example of why Pruitt should not head the EPA.

“Scott Pruitt’s views are so far out of the mainstream that confirming him as the head of the EPA would be a mistake,” Carper told the New Republic. To vet Pruitt’s extreme views, he and committee Chairman John Barrasso, a Republican from Wyoming, have discussed holding longer-than-usual hearings for the nominee—one to two days as opposed to the half-day that is customary for cabinet-level appointments. Carper is also planning on bringing in an outside expert panel to focus, in part, on mercury.

For Senate Democrats, who insist the confirmation is not a foregone conclusion, the hearings are a chance to show that Pruitt is a prosecutor with an inherent conflict of interest with the EPA’s mission to defend human health and the environment. According to Senator Brian Schatz of Hawaii, Pruitt would be a “historical outlier” among both Republican and Democrat EPA administrators, who would shred rather than faithfully administer the Clean Air and Clean Water Acts.