An unlikely partnership of environmental, labor, and trucking groups filed for an emergency injunction yesterday to prevent the Bush administration from allowing Mexican trucks on U.S. roads, claiming that doing so would worsen U.S. air quality. Last week, in compliance with the North American Free Trade Agreement, President Bush called an end to 20-year-old restrictions on Mexican trucks in the U.S. and ordered transportation officials to begin processing permit applications from trucking firms south of the border. Many U.S. truckers are afraid that the move will hurt business, and environmentalists are worried about diesel emissions from the Mexican trucks, which are subject to less stringent environmental regulations than their U.S. counterparts. Some legislators and a Mexican trucking association, however, say labor and environmental groups are taking a tougher stance against truckers from Mexico than those from Canada. The 9th U.S. Circuit Court of Appeals gave the feds until tomorrow to respond to the injunction request.