Arnold Schwarzenegger's administration will sue the Environmental Protection Agency for acting too slowly on California's request to regulate greenhouse gas emissions from automobiles, a spokesman said Wednesday.

At issue is a request the state made in 2005 for a waiver that would exempt it from the federal Clean Air Act, allowing California to more aggressively regulate automobile emissions as air pollutants.

"It's a priority for Californians to protect our environment, and if the federal government fails to act to protect our environment, we will take steps to do so ourselves," Schwarzenegger spokesman Aaron McLear told The Associated Press.

Schwarzenegger will send a letter Wednesday to EPA Administrator Stephen Johnson. The governor was to announce the state's intention to sue during a luncheon speech at the Milken Institute's 10th Anniversary Global Conference in Beverly Hills.

The EPA had delayed acting on the request because the agency maintained it did not have the authority to regulate the gases that contribute to global warming. The state's request was revived earlier this month when the U.S. Supreme Court decided that the EPA does have the authority to regulate greenhouse gases, a position that had long been rejected by the Bush administration.