Governor Schwarzenegger signed a law regulating tailpipe emissions of carbon dioxide, a greenhouse gas. But President Bush refused to allow a required waiver of federal law, even though 16 other states said they'd go along with California. Both presidential candidates promised to overrule the President's order. Now it's Barack Obama who's stuck with keeping his word at the same time the Big Three automakers are threatened with bankruptcy. We get a preview of one of Obama's first presidential controversies.