The Trump administration has drafted a plan to repeal a fundamental scientific finding that gives the United States government its authority to regulate greenhouse-gas emissions and fight climate change, according to two people familiar with the plan. The proposed Environmental Protection Agency rule rescinds a 2009 declaration known as the “endangerment finding,” which scientifically established that greenhouse gases like carbon dioxide and methane endanger human lives. That finding is the foundation of the federal government’s only tool to limit the climate pollution from vehicles, power plants and other industries that is dangerously heating the planet. The E.P.A. proposal, which is expected to be made public within days, also calls for rescinding limits on tailpipe emissions that were designed to encourage automakers to build and sell more electric vehicles. Those regulations, which were based on the endangerment finding, were a fundamental part of the Biden administration’s efforts to move the country away from gasoline-powered vehicles. The transportation sector is the largest source of greenhouse gas emissions in the United States.