But the centerpiece of Monday’s East Room announcement is Mr. Obama’s directive to the Environmental Protection Agency to immediately begin work on granting the so-called California waiver, which allows the state, a longtime leader in air quality matters, to set its own standards for automobile emissions. The Bush administration denied the waiver in late 2007, saying that allowing California and the 13 other states the right to set their own pollution rules would result in an unenforceable patchwork of environmental law. The automakers had advocated such a position, saying it would require them to produce two sets of vehicles, one to meet the strict California standard and another that could be sold in the remaining states.