WASHINGTON, June 13 -- The legal instrument the federal government uses to undo regulation moved again on Thursday, and it pointed at California. The Environmental Protection Agency transmitted four of the state's air pollution waivers to Congress, the procedural step that puts each one on a 60-day clock the Senate has spent the past year using to nullify exactly this kind of rule.

The four rules are unglamorous on paper and consequential in fact, according to the EPA. They cover California's Advanced Clean Cars I emissions standards, its reinstatement of that program, an amendment to its rules on small off-road engines like leaf blowers and lawn equipment, and a 2009 greenhouse gas standard for new vehicles. Together they make up most o...