A group of senators led by Sen. Bernie Sanders wrote to President Barack Obama on Tuesday to express "deep disappointment" in his decision to reject a rule proposed by the Environmental Protection Agency that would have significantly reduced emissions of smog-causing pollutants. "We write to express our deep disappointment, which we believe is shared by millions of Americans, regarding your administration's decision to delay a much-needed and scientifically justified update to the nation's smog pollution standard under the Clean Air Act," the letter said. "We also write to encourage you to protect the Clean Air Act going forward, and to build on its successful, 40-year demonstrated record of protecting public health and the environment, driving innovation, and creating jobs."

To read the letter, click here.