U.S. Sen. Tom Carper sent a letter Monday asking EPA Inspector General Sean O'Donnell to expand the agency's investigation into the new fuel efficiency rules adopted under the Trump administration.
In late February, Carper asked the inspector general to open an investigation into "potentially unlawful efforts and procedural problems" related to the vehicle emissions rules, citing reports received by his office that EPA political officers were dodging certain rule-making and procedural requirements and appeared to be trying to conceal documents critical of the draft rules.
President Donald Trump's rollback of Obama-era vehicle emissions standards was completed March 31. The new rules require 1.5 percent annual increases in efficiency through 2026. The final rules take effect June 29.
In the letter Monday, the Delaware congressman and top Democrat on the Senate Environment and Public Works Committee said his office has obtained new documents revealing "sig…