The Trump administration wants to overturn a key 2009 Environmental Protection Agency finding that underpins much of the federal government’s actions to rein in climate change.

The EPA has crafted a proposal that would undo the government’s “endangerment finding,” a determination that pollutants from burning fossil fuels, such as carbon dioxide and methane, can be regulated under the Clean Air Act. The finding has long served as the foundation for a host of policies and rules to address climate change. The EPA’s proposal to revoke the finding is currently under review by the White House Office of Management and Budget.