Because Trump is unlikely to approve them, California officials say they had no choice but to abandon the state's groundbreaking rules for zero-emission trucks and cleaner locomotives.

California for decades has driven the U.S. toward less-polluting vehicles. It is the only U.S. state with the power to request a waiver from the EPA to set its own, more stringent

California withdrew requests Tuesday for the federal government to allow the state to enforce rules limiting emissions from diesel-powered trains and big rigs in anticipation of the Trump administration rejecting them.